Stephan's Quintet (Hickson 92): Galaxy Cluster
RA: 22 35 57.50    Dec: +33 57 36.0
in Pegasus.

This famous group of galaxies (NGC 7317, 7318A/B, 7319, 7320) was discovered visually by the French astronomer Édouard Stephan in 1877: in fact, the 31.5 aperture telescope employed, made by Foucault, was the very first reflector to use a silvered glass mirror, replacing the older "speculum" metal design. With this super-efficient light gatherer, fainter objects were now seen, aided by an increase of more than 22% in reflectance over the polished mirror surface used by the Herschels. Tammy Plotner opines that "Even with a 12.5" telescope, this author has never seen them as much more than tiny, barely there objects that look like ghosts of rice grains on a dinner plate"; and this statement fairly well matches my own experiences with 17 and 14 inch aperture scopes. While I've seen the Quintet better, using my 10" Dob, in a pitch-dark rural sky at the coast of Central California, my own very first view of the group was at "the site", back in the late 1970s, with Rich Page. In his huge 14" Newtonian, the grouping was barely discernible to my novice eye (a good deal of the cluster may be perceived under excellent conditions with an 8 inch scope, as confirmed from the eyepiece drawing in Jaakko Saloranta's "Personal Challenges" article on his website.)

Now, I can perceive more detail after numerous subsequent experiences; so it was not difficult to find all five galaxies in September, 2006, with my C-11. I found them best seen with a 25 mm "Ultrascopic" Plössl ocular, yielding about 112x, using averted vision and the SkyGlow general LPR filter, making at least the bright central nuclear regions of all five galaxies clearly spotted and differentiated. More detail of the fainter outer regions was found by scanning across the field with a 17 mm Plössl, and no filter. At lower power, the general glow of the background sky inhibited the observation. In the 8-minute square image, above, from the POSS-1 blue plate, a minute and faint galaxy is seen at the far left edge: it is NGC 7320C (or PGC 69279), 0.6 x 0.2 arcminutes diameter, which is also probably a member of the group. I did see this also, on 26 September 2006, stating that it was finally "visible (after great effort), as I scanned across field with 9 mm [310x] at edge of detectibility."

Another galaxy is possibly related: NGC 7320A (MAPS-PP E_778_793138 or 2MASX J22363213+3347456) which looks like a faint edge-on flat (spiral?) galaxy on the Deep Sky Survey plates, located about a dozen arcminutes to the SE of Stephan's Quintet. I was able to detect this too on the same occasion, using a 12.5 mm high-efficiency Lanthanum eyepiece, and later confirmed it with a second observation with a 10 mm Plössl (views at 224x and 280x, respectively.) I made a final test to see how high the magnification might be, and still show the galaxy: it was discernible with a 7.5 mm Lanthanum, yielding 373x! So, the lesson is not to be afraid to use high power for faint, small-angular-diameter objects.

7320A and 7320C are challenging and faint objects, rated respectively at 15th and 16th magnitude visually by Steinicke: difficult catches for an 11 inch aperture scope. Steve Gottlieb comments here in his overview of NGC objects about the challenge of observing NGC 7320A, even with a 17.5 inch aperture scope in a pristine dark sky venue: "a difficult object and not seen when the GSC position was first examined. Finally, with averted vision a very low surface brightness glow was occasionally glimpsed." I can't disagree with a single word of that; but I used a scope with a theoretical light-gathering factor that was only about 40% of Gottlieb's big Dobsonian -- and in a "mediocre" sky, not far from the Santa Clara valley light pollution!

7320C might have been, for me, an even greater achievement: Steve Gottlieb says of his sighting with a 17.5" aperture scope: "Only glimpsed momentarily so observation not certain but repeated a few times... from excellent skies in the White Mountains (12,500' elevation)." But Gottlieb doesn't indicate that he was using supplemental oxygen, which is almost certainly necessary for optimal visual observing at such a high altitude! The blood oxygen level at twelve to fifteen thousand feet above sea level will drop below maximum saturation, and will greatly impact one's faint light detection capability (according to my own interview of Dr. Kelvin DeGinder, the high altitude medical consultant to the Keck Observatory in Hawaii, as recounted in this installment of my Horsehead research.) At the 13,798 foot summit of Mauna Kea where the Keck telescopes are located, oxygen bottles are absolutely essential for the workers and astronomers; and this is not much higher than White Mountain. So, I'd tend to wish to know much more about Gottlieb's observing session before I'd assume that his observation of 7320C is applicable to all other circumstances.

The rarity of visual observations of 7320C became evident to me when I encountered a post to the Yahoo group "amastro" (for advanced deep sky observers) by one "Stan H." who wrote on October 5, 2007 that he could not see it with his 17.5 inch telescope, inquiring if others had done so with a similar instrument. I'll be interested to know who has done so, other than Gottlieb.

In late summer of 2007 I attempted to discern the Quintet with a new telescope: a 120 mm (4.7 inch) aperture f/5 refractor. I was only able to tell that there were galaxies present, in a sort of faint smudge (discussed here in greater detail in my astro-blog, slightly more than halfway through the long report of observations made in mid-September.) So, I have to conclude reluctantly that this wonderful celestial phenomenon is not going to be very satisfying for users of very small scopes!

Jeff Medkeff, a former contributing editor of Sky & Telescope, has written an excellent webpage about making an observation and drawing of the Quintet by employing a 10" aperture scope, which is found here. Unlike so many other amateur astronomers' websites, Jeff's is "information intensive", with lots of informative text, cutting through the cant, biases, and old wives' tales of optics and amateur astronomy: I highly recommend it. You may find Jeff's astronomy page menu here.

A very succinct page about the galaxy cluster is found here at the Skyhound website. For a fabulous ground-based color image, made with a 20" Ritchey telescope, click here; a "closeup" of the central region, taken by the Hubble Space Telescope, is here.

Posted first in 2006; amended, updated with information on 7320A and 7320C on 5 Oct 2007.

Faint stuff! These three obscure galaxies may be found within a region of about 8-9 arcminutes, and will all fit into the eyepiece field of my 21 mm Stratus eyepiece, yielding 133x in my C-11. Yet, at "the site" near San Jose and south bay light pollution, they are by no means immediately visible. Irregular galaxy IC-5377, the barely discernible smudge to the right that forms a triangle with fairly bright 10th and 11th magnitude stars, is rated at 14.7 visual magnitude and measures 1 x 0.6 arcminutes diameter: I found this object to be at the very threshold of detection on the night observed (late September 2006), which could have had less light and more transparency if conditions had been better. It was seen -- or so I thought! -- only with the higher power of a 17 mm Plössl (164x) using various techniques to make faint nebulosity show up: averted glimpses; bumping the telescope slightly; and slowly sweeping across the field. The two more obvious galaxies to the left are IC-5378 (an elliptical of 14.6 magnitude, 1 by 0.9 arcminutes) and tiny faint IC-5379 below it (15.2 magnitude, only 0.4 by 0.2 minutes.)

The former, IC-5378, looks on the POSS-1 plate image above (25 minutes square, about the same field as my 21 mm Stratus ocular in the C-11) like a smudge next to a star; but a cropped, magnified, and highly enhanced view of it -- to the right -- reveals that the bright spot is not stellar but rather the nuclear region of the elliptical IC-5378, surrounded by a trace of its outer halo, intersecting with a fainter galaxy just above it on the image: the two objects are no. 130 in the catalogue of Halton Arp's Peculiar Galaxies. Needless to say, these details were not visible in my telescopic eye-view.

IC-5378 and 5379 were discovered by one of my favorite astronomical figures of the 19th century: Dr. Isaac Roberts, discussed by me in relation to the Horsehead nebula in this article. Roberts found these two galaxies on a plate he exposed with his 20" telescope on Nov. 17, 1895 (all of his photographic discoveries are detailed here.) If you do more research on the net about these objects, be aware that there are mistakes in certain webpages: one attributes the wrong Arp number (in an otherwise authoritative website about the history of the NGC and IC.) Another page has a series of observations by astronomy club members, by constellation: IC-5378 is identified as being "nonexistent", implying that it was a catalogue mistake (NO!) And another article gives a discovery date that is ten years off. The moral: search deep, and confirm what is asserted on any single website, if possible.

What can you see by eye, versus a photograph? What, indeed, if your eye is PREJUDICED by a celestial photo? This particular object caused me uncertainty and consternation, since I could not confirm what I expected to be able to see, based on viewing a picture in dim light on my laptop, during the observing session. When I had a chance, later, to review the object in the daytime, obtaining various other images on the net and studying details, I decided that my eye view was correct, and that my perception of the photo was inaccurate. This suggests that using pictures, at the telescope, will sometimes mislead the observer!

The issue is the exact nature of the galaxy, and whether it is seen as a spiral, or a sort of tortured, peculiar one (such as the so-called "Hockey Stick" galaxy, NGC-4656, in Canes Venatici.) Up at "the site" on an early September morning in 2006, I was looking at a photograph in the Tom Trusock Small Wonders article about objects in the constellation of Pegasus, and methodically going through each one with my C-11 telescope. Trusock stated that his article's photo was a particularly realistic depiction of the galaxy as seen under certain conditions with an amateur telescope: could I replicate this view with my equipment?

My effortful technique of using a laptop at night is to do the following to preserve my dark adaptation: (1) I employ a deep red plastic filter across the entire LCD to block colors that would reduce my dark adaptation; (2) I decrease the screen intensity to one-forth the level used during the daytime; (3) I cover my observing eye -- my "good" right eye, with little astigmatism -- with a black eyepatch, and view the computer screen with my poor, fuzzy left eye only; and (4) I have to use two levels of magnification on the left eye (glasses, and +2.75 reading lens magnifier) to make up for night myopia. When I'm through examining the computer screen, I move the eyepatch off the RIGHT "telescope" eye, and put it on the LEFT "computer" eye, and then look into the C-11's ocular. My dark adaptation is thereby retained. But...there is a hitch!

The picture (to the immediate right) that I studied of NGC-7479 seemed -- in the dark red dim screen view -- to show a "hook" below the galaxy, as though it was a perturbed, interacting one. In reality, it's a distinct spiral as shown in the POSS-1 blue plate that I cropped and rescaled, above. The "hook" disappears when the image is shown properly, with full illumination, and the other, dimmer spiral arm comes into view. But, at night, I had erroneously prepared myself only to see the spurious "lower hook". I tried and tried to see that; but failed! In my eyepiece view, using varying powers of magnification, I saw merely a general oval glow that had varying intensities: no "hook". I shrugged this off as "too small an aperture". Was I right? I have attempted to modify the POSS image in the second picture to the right, immediately above, to resemble my eye's perception.

After further reading about the galaxy, it turns out that I should not have trusted at all my perception of a computer picture in very dim light! The "eye view" is a fair representation of the galaxy, minus the exact details of the arms that would show up in a long photographic exposure.

NGC-7479 is not by any means a "challenge" object: its visual magnitude rating is 11th, and at a 4 arcminute diameter, the surface brightness is reasonably high. The challenge -- if any -- is to see THE DETAIL, as closely by eye as films and CCDs can record it accurately.

The eye has its limits. Just as I have been unsuccessful, over the years, in getting a clear eyeball registration of the famous Pillars of Creation in M-16 (though the overall glow of nebulosity is always visible in any telescope), I have also not been able to trace out the Mountains of Creation, the fanciful name for the newly-discovered stellar nursery W5, uncovered in a fabulous Spitzer Space Telescope image of IC-1848. I take consolation in the fact that the original discoverer of the "cluster with nebulosity", E. E. Barnard, probably never had an inkling of what science would eventually uncover.

At "the site", the Cassiopeia region is often lost in the overall light pollution glow from the southern edge of the San Jose-Morgan hill valley. But, miraculously, enough fog and haze had moved in on the morning of 24 September 2006 to give me a few choice views of objects I never bother to observe. IC-1848 appeared, in the C-11 scope's 21 arcminute FOV using an "Expanse" 15 mm ocular, plus a SkyGlow general LPR filter, according to my notes as "two tiny groups of stars with nebulosity": sadly, nothing like this fabulous h-alpha image by Tom Carrico, taken with a 4" aperture Takahashi astrograph. If you have a wide-angle scope with a faster focal ratio than my C-11, you may be able to make more of the entire beautiful region of rich nebulosity, as in this colorful picture by Jerry Lodriguss. He explains that the nebulosity around the cluster IC-1848 is now catalogued as LBN 667. The object is colloquially dubbed the "Soul" nebula, probably because it forms a pair with the close-by "Heart" nebula, IC-1805. This "Atlas of the Universe" detailed webpage about the pair of objects shows a helpful isophote plot which illustrates clearly the exact region of the star cluster IC-1848 that is centered in the picture I've produced to illustrate this description. That image, above, employed a 20-arcminute wide capture of the POSS-1 red plate. Since the human eye is not sensitive to faint red wavelengths, I had considered employing the blue plate; but it registered far less of the nebulosity than my eye could actually see, using the C-11. So, I've "toned down" some of the glow. I can't claim that I could discriminate the fine variations in nebulosity, but the extent of the soft milkiness is not far from what I observed in about the same eyepiece field.

"Barnard's Loop", as it has been dubbed, is a large gaseous cloud, the remains of something that happened eons ago in the region of the famous "hunter" asterism of the constellation of Orion. There are various theories: it may be a supernova remnant, a diffuse nebula excited by a group of very hot young stars, or a gigantic bubble of gas formed by a series of supernovae. For photographers, it is not particularly challenging. You must have a dark sky free of almost any manmade light pollution, a "fast" lens (f4 or less), and considerable patience (exposure times of 3-4 hours are not inappropriate, though CCD sensitivity reduces this to perhaps 20-30 minutes, as in this composite hydrogen-alpha image by David M. Jurasevich.)

The region I describe below, observed by me with binoculars, is centered at the top set of coordinates, above, and depicted within the bright rectangular region in the picture. The entire nebular cloud extending across the constellation of Orion is known as Sharpless 2-276, whose official coordinates are the second and lower set in the picture's caption. Really, the exact coordinates of this gigantic expanse of space are not crucial...for visual observers. Since the angular diameter is so large, one need merely look up, and to the east, of the famous, unmistakable belt of Orion.

I have seen at least parts of this vast expanse of faintly glowing gas a number of times, but only when the sky was pristine-dark. Before the eruption of Mt. Pinatubo in 1991, I saw it with 11x80 binoculars at "the site", but not after that until 1 October 2006: nearing morning twilight in a short early morning session that was 'captured' just between the passing of vast swatches of clouds from the Pacific ocean. Severe, dense fog had settled in over the entire SF/SJ bay area, leaving me exposed to the clear sky at the very tip of the mountain range south of San Jose, the fog bank only a few hundred feet below me. At the end of a long, tiring night, I beheld the wonderful sight of Orion nearing the meridian, with a vast sparkling stream of northern Milky Way stars coursing down through the asterism: this diamond dust effect rarely seen at "the site" due to light pollution. Now was surely the time to look for Barnard's Loop! And find it I did, with a lowly pair of 10x50 binoculars I had purchased a few weeks earlier at a clearance sale for $30: "junk" binos to throw in my car for utility use. The loop was not as brightly seen, nor as widely traceable, as it had been in the late 1980s when I got my all-time best views in a dark Central California coastal observing site with 11x80 high-end binoculars. The cheap 10x50s barely had any coatings; yet I could see not only about a third of the loop's path but also IC-2118, the Witch Head nebula, two and a half degrees west of Rigel. Unfortunately, it was only a large amorphous, faint glow; nothing like this fabulous color image by Russ Dickman. I doubt that much of this detail -- and certainly none of the brilliant blue color of the "head's" excited gas cloud -- could ever be visible by eye in any conventional amateur scope.

The Loop radiates many different wavelengths of light, although images such as this vivid color rendering by Dr. Wei-Hao Wang suggest that it glows merely in the red wavelengths of hydrogen-alpha light. However, wideband detectors may discern ultraviolet light as well as visual-range starlight reflection lightwaves. The dark-adapted human eye, aided by the right optics, is sensitive to the higher frequency of hydrogen-beta, and in this greenish color the nebula's brightness does not match the h-alpha density (as recorded by my friend Chuck Vaughn's remarkable 90 minute composite exposure on Tech-Pan film.)

It seemed to me that the brightest spot of the nebula was near the star HR 2113 (SAO 137732); so I prepared a crop of that region from the red POSS-1 plate, which was apparently near the edge since the National Geographic's label was partly shown. To the left is a cropped region of a few arcminutes around the star, with the vague nebulosity seen at the right of the image. I have also segmented part of Chuck Vaughn's monochrome image, and enhanced it slightly: in this rendition, the nebulosity just to the west of HR-2113 (which was outside the field of the photograph, past the left edge) is more clearly discerned, though to my eye it was a featureless bland glow. One can see more than that, given perfect conditions and the right equipment with appropriate wide fields and bandpass filters: Dave Riddle's excellent article discusses his many detailed observations by eye, using optics that are much more powerful than my cheap binoculars.

I would have made more of the observing session, but as I scanned through the region I began to notice a bright glow to the east: the zodiacal light, occurring about a half hour before sunrise. The sky slowly began to resemble the vague milkiness of silicon valley light pollution: not from streetlights, but from the dust particles of the solar system, reflecting the glow of Sol. I have rarely seen this phenomenon at "the site", but when it IS visible, it quickens my pulse! It was as pleasing to view as Barnard's Loop.

Once again, as in my research on the Horsehead, I found in searching the Net for information about this celestial wonder that webpages are riddled with inaccuraries since most articles merely digest second, third, fourth sources without bothering to check ORIGINAL publications. I've done so. If you bother to read my long paper about the 19th century research that led to photographs of the Horsehead and Orion region, you will obtain direct quotes (with source attributions in footnotes) that give the authentic history. In brief, the loop -- found in one of the "52 regions affected with milky nebulosity" discovered visually by William Herschel -- was first photographed by William Pickering in 1889 at Mt. Wilson with a 'fast' camera; Edward Barnard acknowledged that when he wrote about his own first image, taken on December 1894 "with an ordinary child's magic lantern lens", and later before he left Lick Observatory with the Willard camera lens used for Barnard's plates of the Milky Way; finally with "with a small, cheap lantern lens belonging to Professor Hale." On the night of January 17, 1903, Barnard obtained a plate of the great curving nebula that was "clearly shown, especially the region described by Herschel..." ("Diffused Nebulosities in the Heavens", Astrophysical Journal, Vol. XVII, January - June; Chicago: University of Chicago Press [1903] p. 77.) In this article, which rebuts the claims of Dr. Isaac Roberts that nebulosity could not be found photographically in most of those regions, Barnard explains that Roberts' exposure times were too short. I have seen an early published print of the original first Barnard image, taken at Lick Observatory, as well as his later ones. Much of what may be recorded on fast film today, or by CCD, is visible; but the star images are severely deformed and distorted at the edges on the picture taken in 1894 with a simple lens. So, the photograph by amateur Chuck Vaughn truly marks an increase by at least an order of magnitude in beauty (and useful data) over what the then world's best professional astrophotographer -- Barnard -- could do a century earlier.

Finally: as an aid to observers, I have created two charts, one shown here that illustrates the region of the Loop that I found to be brightest (the green rectangle, encompassing the star HR 2113). If you wish to print this chart, you may prefer to use a negative black-on-white version: click here to open or download the file.

These charts were created with "Cartes du Ciel", the freeware star chart program for Windows, provided as a great public service by Patrick Chevalley.

On the blustery morning of 18 October 2006, while doing a night of comet-observing (C/2006 M4 Swan, 4P/Faye, 177P/Barnard, and C/2006.T1 Levy: I saw them all!) I used my 10" f/4.7 Dob at "the site", during long intervals between the appearance of the morning and evening comets, to look at a few favorites but primarily at objects I had seldom viewed. After ogling NGC-2174, described above, I swept my telescope to the fabulous open cluster M-35, and then to all the fainter objects in the region around the brilliant sparkler, 3.7 magnitude double star 7-Eta Geminorum, also commonly known as Propus (SAO 78135, shown in the center of the cropped POSS1 blue plate image, to the left, chosen by me to attempt to replicate the pale effect of nebulosity as seen by the live telescopic eye.) Astrophysicists calculate that a supernova occurred when a star collapsed approximately 30,000 years ago, leaving a huge "bow shock" wave of gas, with an embedded neutron star. A wide-field view of the region in monochrome, recording more of the wavelengths of the excited gases than the Palomar plate, illustrates the fascinating and complex nebulosity of both IC-443 and nearby phenomena: the remarkable shape of the expanding nebular cloud is a clear revelation of why this object has acquired the nickname "The Jellyfish" -- but I'm sorry to say that with merely a 10" aperture scope, this detail is not vividly apparent to the eye. This narrower-field view, presented as a negative image taken in hydrogen-alpha light, shows amazing felicities, as do these composite multi-wavelength images depicting in addition the other objects in the immediate region: IC444, Cr89, M35, NGC2158, NGC2168 and Sh2-247. One of the Jellyfish's most staggering color images on the Net was done by my friend Chuck Vaughn. It is instructive to compare these pictures by amateurs to the best that professionals could achieve up to the introduction of digital imaging. Truly, amateurs are now surpassing some of the best professional earth-based astrophotography up to the 1990s.

I was able to detect, on a night with absolutely no helpful ground fog below me, leaving a bright, distracting horizon glow from Morgan Hill and Gilroy, much of this nebulosity by eye, sweeping across the region with a 32 mm Plössl ocular and an Orion "UltraBlock" hydrogen-line nebular filter (38x, 1.4d FOV, 6.8mm exit pupil), also examining the specifics more closely with an Orion "Stratus" 21mm ocular (57x). I could see a fine tracing of faint way lines -- reminding me of parts of the "Veil" Nebula -- near 7-Eta, as similarly shown in the Palomar picture given above, and also noted a beautiful general glow around Collinder 89 (which Matt Tarlach confirms in this report of observations made in a much darker sky in the northern California motherlode country.) Two mornings later I observed the objects again but in sky conditions that did not match the previous experience, with even more light pollution. I had piggybacked my 80mm aperture f/5 refractor on the C-11 scope to compare exactly the same coordinates, but in a 3-degree field at 20x in the refractor (magnification too low for the Schmidt- Cassegrain.) Despite faint skyglow, the small diameter lens yielded lovely views of the nearby star clusters, and distinct wavy nebular 'puffiness' in the densest part of the Jellyfish, using an UltraBlock filter; and with an O-III filter for maximum contrast, at 13x, the dark lanes in IC-444 could be detected. Truly, one can spend as much time as one likes in studying this inexhaustible, rich, fantastic celestial region!

• Link to Jaakko Saloranta's observation by means of an 8" Dobsonian scope.

The great eagle-eyed astronomer William Herschel invented the term planetary nebula about the same time that America's Benjamin Franklin, not blessed with comparably acute vision, invented bifocal glasses! Four years earlier, Herschel had attained celebrity as the discoverer of the green planet Uranus. When he began his first extensive surveys of the heavens, Herschel noticed strange -- sometimes greenish -- disks, ovals, and smudges of light, which were distinctly non-stellar: because of the resemblance to Uranus, he dubbed them planetary nebulae. In the Herschel survey of objects, this particular nebula was designated as IV-34, and was first seen in 1785 with the 18-inch speculum metal reflector telescope.

The image prepared here for this entry shows a square of 8 arcminutes with the nebula centered, approximately equivalent to the field diameter I viewed in my C-11 with a 7.5 mm Orion Lanthanum eyepiece, providing 373x. The nebula was, simply, spectacular: bright, clear, well-defined, and requiring no filtration. It jumped into view as soon as I put the scope onto the field, using 133x with the widefield ocular I usually employ for initially identifying objects with this scope. The inset, lower left in the picture, was cropped and processed from a CCD image taken by the Palomar-Quest survey, magnified, sharpened, and contrast-altered by me (with the brightness of the "edge" star increased) to resemble approximately what I could see during flashes of clearest resolution using my 3.7 mm Orion Epic ocular (an amazing 757x!) I wrote in my observing notes, "Lumpy with 6mm, 467x. With 3.7mm, saw flashes of two stars inside nebula, and much variation in brightness across oval disk." (For a clearer color view, see this astounding ground-based image taken with a 16-inch aperture Ritchey-Chretien scope by Adam Block.)

This nebula is definitely not a dark-sky challenge object; it was in fact barely visible to me using low power in my 80mm f/5 refractor on the morning of 20 October 2006 at "the site", in clear, transparent seeing but with light pollution all around (naked eye stars dimmer than about 5.2 magnitude being nearly impossible to see with straight-on vision.) So, why include the object here? Because of the internal star, and the surface details! A web search yielded some interesting observations that I compared to my own. The experienced sky hunter Yann Pothier, in France, used a 17.5 inch aperture Dob (a brand identical to one that I owned years ago, but got rid of because its appallingly bad resolution), and reported that in excellent transparency but average seeing, there was "no central star from 145x to 624x (even with prism)" though he could see a "darker center at 312x". Using what would seem to be a scope of similar size and design, Lew Gramer of Massachusetts wrote in 1999 that he found the object at first to be "annular"; striving to see the central star, he determined at high magnification it was an optical illusion. Yet, he seemed to perceive an "incipient inner ring" and "bipolar lobes" that are not borne out by the photographs and CCDs that I have examined. With an 8-inch SCT, Jeff Burton perceived only "a small, faint, round, diffuse ball of light" (but, his apparently younger eyes than mine were able to detect that "With direct vision, the planetary nebula is tinted light blue"; even with as large an exit pupil as I could manage in my C-11, it seemed to me to be a colorless gray -- a typical result, as I have known for some time that better and more youthful observers often see delicate telescopic colors I can't discern.) And, in the NGC/IC Project public database entry for NGC-2022 -- not immediately linkable here -- expert observer Steve Gottlieb reported that "No internal structure was visible" using his 13" fast reflector, and that there was no sign of a central star with his 17.5".

But, can it be believed that no more than ten or fifteen miles from the valley floor of San Jose that I can claim, with an 11" scope, to have seen "flashes of 2 stars inside", including the central star? Various references on the Net indicate values from 15th to 15.8 magnitude for that star; and I have definitely spotted fainter ones than that, in best moments of steady seeing, with the C-11. The contrast must be exactly right for stars to show up inside the glowing interiors of planetary nebulae (M-57's central star, described above, is an especially frustrating one.) One must also avoid the optical illusion of mistaking central brightening inside a roundish extended object. This is prevented by using high power and critical focus, watching patiently for a precise stellar point of light.

My C-11 optics -- unlike those of all too many bigger aperture Dobs -- are very good (showing, in fact, text-book perfect in-and-out of focus diffraction patterns.) The laminar airflow at the peak of the mountain range where I observe, at 3400 feet, often produces seeing equivalent to nearby Mount Hamilton's Lick Observatory (where Barnard spied not the expected canals of Mars, claimed by astronomers with poorer telescopes and locales, but canyons, chasms, and craters, to his amazement.) I also work hard to achieve profound dark adaptation, keeping my right viewing eye under a black patch at EVERY moment it is not looking into the eyepiece. After several hours of observing, my eyes are at maximum acute sensitivity.

Furthermore, seeing extremely faint stars, dimmer than the approximate "theoretical" limiting magnitude given as general guidelines for scopes of various apertures, requires time and patience. Celestial seeing conditions here on earth are never absolutely steady; one must wait until an accumulation of "100 millisecond glimpses" of sharply resolved faint stars will fully register on one's conscious perception. This means you probably have to use a motor driven telescope to track the object, as well as the highest magnification your optics and the sky conditions will support. A huge Dobsonian telescope, using 600x magnification, must be constantly moved in two axes by the hapless observer, or the faint object under investigation will be out of the eyepiece field in a couple of seconds! To me, there is little surprise that few users of 17.5" Dobs see the faintest, dimmest details such as the central stars of many planetaries. Doing so is, in fact, an almost physically insurmountable task with such an instrument (although, of course, at lower powers, or for faint extended nebulosity, a 17-incher can 'blow away' an 11-incher.) So, is my claim here of seeing details that show up well in the Adam Block picture -- at least in 'black and white' -- using a tracking scope of high precision entirely unbelievable? Well, I still wouldn't blame anybody for being a mite skeptical if other comparable descriptions achieved by similar sized motor-driven scopes aren't readily found ... try and see what you can achieve.

• Link to Jaakko Saloranta's observation by means of an 8" Dobsonian scope.

This faint planetary, with an 'official' diameter of 59 arcseconds, largely radiates the reddish tinge of hydrogen-alpha light, looking like an uneven, oval, broken, overlapping loop: as shown in the lower-left insert in the picture given here, taken in red light by the POSS-1 survey. The larger main picture was done in blue light, recording the weaker hydrogen-beta line; I chose that frame since the human eye is not sensitive to faint red wavelengths, so the blue plate is closer to the faintness of the image in the eyepiece of a large aperture scope. Even so, it was fainter still in my C-11.

A lovely color image taken with a C-14 may be found on the web page of Carl Burton, and an interesting large-scale CCD image is found here. Apparently the distinctive shape of the object has helped it to acquire a nickname, as it is known among amateur astronomers (that is, the select crew of observers who go after such challenging prey) as "The Snail Nebula". Like such a creature, the observer must proceed at "a snail's pace" to find, and get the right combination of eyepiece and filter to see, this test of one's determination.

In the Abell catalog of planetaries, objects discovered on Palomar plates by Dr. George Abell in the 1950's, No. 79 is described as having a magnitude of 15.3, with a surface brightness of 15.06 magnitude per square arcminute. As observed with a 13" scope in a very dark sky, "Deep Sky Dave" reports on that web page that Abell 79 appeared "Extremely faint. Roundish object. Faint asterism of stars in field of view. Switched to 4mm (9mm Nagler and 2X barlow), 350X and used averted vision. Faint glimpses of a roundish shape. In and out of view, could not discern true size or exact shape. Very Faint. Star seen in middle...not sure if it is [the central star]" (emphasis by SRW, for reasons elucidated below.)

My observing notes for the morning of 19 October 2006 -- 'cleaned up' a bit, without scribbled abbreviations -- stated that it was "barely visible with C-11, sky naked eye limit about 5.5 with no ground fog and light pollution evident in the region. I suspected its presence with 186x (plus UltraBlock filter) in a field of view of about a half degree; increasing the magnification to 224x (12.5mm Orion Lanthanum eyepiece) gave a better view. The O-III filter did not help. Finally I settled on a 17 mm Highlight Plossl" -- an eyepiece having excellent clarity -- "yielding 165x with an exit pupil of 1.7mm, which still allowed the UltraBlock to work without severely dimming all the light. It seemed to consist of an extremely evanescent trace of a ghostly faint uneven ring, covering small central speck in the 18-arcminute eyepiece field. My guess is that it looks like a small disk, apparently around a very faint central star that was just visible in steadiest seeing. Averted vision absolutely necessary, plus great concentration. Is this the faintest planetary I have confirmed, so far?"

I had no information about the object at hand, other than its position and diameter; so these impressions were honest and unbiased.

How many other observers report seeing the central star in posts on the Net? Not many. Stathis Kafalis says he saw a 14th magnitude star in the center of the nebula, using a 24 inch scope, but isn't sure it was the central one, which he asserts might be '17.6'.

In truth, there are conflicting data about that star magnitude. I found nothing conclusive on the Net, but I was informed by a friend who has the computer program "Guide" that the information file for the object states that 'according to the PK catalogue', it is rated at 17.6...yet, that datum is not included in the official updated year 2000 version of the PK catalogue found complete on Dr. Lubos Kohoutek's website. And, the amateur database of deep sky objects published by the Saguaro Astronomy Club claims that the star is 18.4 magnitude: it would SURELY be impossible for me to see a star that faint in my C-11!

How about users of larger aperture scopes? Yann Pothier, using a 17.5" Coulter Dob, does not report seeing it. Neither does Steve Gottlieb, though the nebula itself was visible to him even without a filter in his large aperture reflector in a dark sky site. The central star was not visible to Doug Snyder, nor apparently to Alvin Huey, using a 22" aperture Dob. Steve Coe calls the nebula a "toughie" and does not mention the central star; nor does Eric Honeycutt, who seemed only to suspect "a central hole". I am beginning to wonder if, in fact, I'm crazy! A possible explanation of my "impossible" sighting could be suggested by this comment in an article of Planetary Nebulae Observation Reports: "by removing the O-111 filter [in a view with a 17.5" scope] several faint stars are superimposed at the position of the planetary although Abell 79 was not visible." Perhaps the exact center of this very faint object was obscured by its dimness, and I thought that one of those "superimposed" stars was the central one. Well, it's a working hypothesis...I like it better than saying "I must be utterly deluded!" (or, as other amateur astronomer friends of mine might grumble, "oh, there goes Waldee again: full of it, as usual.")

Probably the solution to my quandary has been provided by Benjamin Mauclaire, responding in the Yahoo Planetary Nebula group, who answered my question about the star's true known magnitude. "SECGNP [Strasbourg-ESO Catalogue: found on this page -- srw] gives an 'old' photographic mag_pg = 18.7 that seems to come from Perek-Kohoutek 1967's survey. It's explained that B mag can be computed by adding 0.6 to m_pg with an accurancy of 1 mag." That does it: there is simply NO WAY that a 17th or 18th magnitude star could be seen by a human observer, using an 11-inch aperture telescope! I saw another star, not the central one, or perhaps scintillations occurring in the region of nebulosity.

Update, Nov. 2006: Now I have somewhat more confidence in my own observation. In answer to a request I made in the Yahoo Planetary Nebula group, Howard Branich has made an observation which tends to corroborate what I have reported seeing. He has made a superb drawing and posted a web page of his observations; in addition, he states in the Yahoo group that "I had a chance to re-observe Abell 79 this past Friday night in pretty decent conditions...I concentrated on seeing the central star and found two candidates and I'm fairly sure one of them is the central star. As I mention in my observation notes I'm not all that accurate in estimating star magnitudes, but the fainter one seemed more like 16th magnitude than 17.6." If so, then it is possible that I spotted it in a moment of spectacular sky steadiness at "the site" in the Santa Cruz mountains, with my C-11! It may not be the central star, but it was surely one of the two that Howard drew in his sketch.

Furthermore, the subject I initiated in the Yahoo Planetary Group evolved into an extensive and productive discussion about visible stellar limiting magnitude with scopes of diverse apertures. Some of the expert viewers, like Howard, had confidence that an 11" scope could show a careful observer a 16th magnitude star. Eventually two links were posted to articles that are worth perusing: Through an Eyepiece Darkly, by Dave Gill, which quotes research by Roger Clark indicating the "outliers" who can see a bit fainter than average, with possibility- percentage calculations, and the best and most thorough limiting magnitude calculator that I've seen, based on Bradley Schaefer's program, on Larry Bogan's website. When I estimated the numbers of my own situation as accurately as I could, the program reported that my C-11 stellar limiting magnitude might reach 16.37 under the conditions I tried to define: close to what I am now experiencing in the field.

Well, central star or not, one of the ratings given for this planetary nebula -- in a starchart program on my laptop -- claimed 15.8 magnitude. THAT is a dim 'nothing' to be able to detect with an 11-inch scope, especially this close to civilization. I have no doubt that had the sky background light dropped, if some ground fog below me had formed, the barely visible details of this object would have been much easier to comprehend.

Update: You may read about my next observation of Abell 79 in November 2007, with my 10" scope, by clicking here for this observing blog report.

Wide Finder Chart        0.5d Eyepiece View Chart: upright, correct

This is a phenomenal region of the winter sky, about 2-1/2 d SE from M50, and 22 degrees SW from M-42, crossing over the boundaries of Canis Major and Monoceros. The likely explanation of this arc of glowing hydrogen gas is that it is a supernova remnant. In an extremely wide field photograph, turned at an appropriate angle, it tends to resemble a seagull in flight; bright/dark emission regions forming a distinctive head and beak -- though, to my eyes, the object is rather like a parrot's head tacked onto a seagull's body and wings.

The processing of this wide field photo by Matt BenDaniel causes it to resembles most, of the ones I've seen on the Net, the shape of a seagull; however, this fabulous digital image by the amazing Walter Koprolin, taken in a dark Austrian rural sky, may be the greater technical achievement.

Another view, with closeup of VdB 93 section of IC2177, is here in a Kitt Peak image by Fred Calvert and Adam Block.

The highly-experienced amateur astronomer Richard Jakiel comments in an article in the Saguaro Astronomy Club newsletter: "An interesting target for astrophotographers... The Seagull can be found by starhopping north from Sirius to Theta Canis Majoris, and then proceeding about 2.5 degrees due east. This will bring you to the southern section of the nebula... Moving northward, another bright “knot” in IC 2177 is NGC 2327... a small reflection nebula that surrounds a 10th magnitude star. Along the northern 'wing' of the Seagull lie a number of small clusters embedded in a rich star field. These are a delight to the eye and help enhance the view of this subtle nebula."

I have not had an opportunity since the early 1990s to view the southern winter constellations in a really dark sky, and have forgotten most of my experiences of this particular object, since I suspect I have not seen it since observing with Rich Page in the 1980s. In the heart of winter, "the site" is cold, forbidding, windy -- and fog-free. Glow from Hollister and Monterey can wipe out faint details. Unfortunately for the glories of the "Seagull", during that period of past time I was most interested in the Horsehead and immediate surroundings, and slighted some of the other gems, further down toward my southern horizon. (May one admit that if you finally begin to tire of the Horsehead, you're becoming a bit jaded?)

It was a completely unexpected experience, on the morning of the last Sunday in October 2006, to look up from the eyepiece, in a rather milky and washed out sky during most of my night's observing, and to realize that suddenly greater darkness had fallen around me: the light dome toward Hollister had winked out, and most the glow from Morgan Hill was cut off by a temperature inversion and fog layer. It was nearing 5am and astronomical twilight, so I got quickly in gear and shifted my observing into the best sky in the Canis Major region I'd seen in many a night.

I reckoned that the great challenge in the area would be Gum 1, "the Seagull", a gargantuan field of glow that was -- unfortunately -- rather unsuited to my narrow-field, high power C-11; but what details could be gleaned across this vast expanse?

The POSS-1 blue plate image included here covers about the eyepiece view in my C-11 with a 42 mm 2-inch barrel Plössl, about 45 arcminutes' diameter. An even wider field would be preferable, if the observer has a large-aperture rich field scope available; in my 80mm f/5 refractor, with an ocular yielding a 2d field, there was not enough light gathering to make an effective use of a nebular filter, and the sky background brightness washed out the nebulosity under my particular circumstances. But, my UltraBlock filter worked well in the larger telescope; without it, there was nothing except stars and a dim bland sky background: no nebula.

As I slowly swept around the area defined by the isophote for Gum 1 plotted in my telescope-control planetarium program, I decided that the visually brightest patch was between SAO 152320, a mag 8.1 B0 star, and the dimmer 9.3 mag star GSC 5385:1522; so I have prepared a field of view chart with superimposed Telrad reticle, the 1/2 degree circle centered approximately on the spot where I could definitely the see fine tracery of narrow nebular streaks, using my 21mm Orion Stratus ocular and either an UltraBlock or O-III filter.

Before I could carefully study and plot IC-2177, astronomical twilight was upon me and the sky quickly brightened, eliminating all chance of seeing VdB 93 and Sh 2-292 in the "seagull's head" area. I hope I shall soon be able to return to this object during an equally dark morning, weather and ground fog cooperating!

Finally: while preparing this entry I was perplexed by the seemingly- irreconcilable differences in the resources I had at hand. "TheSky 6" planetarium program identifies the region as "Gum 1", based on the Saguaro Astronomy Club database. Delving further directly into the lists published by that organization, I found that Version 7.2 lists Gum 2 as being coincident with IC-2177 -- this is the designation used by Jakiel -- and in the later version 7.7, Gum 1 is coincident with Sh 2-292. Earlier version IV of TheSky, owned by a friend, seems to plot the entire area only as "IC-2177" over a diameter of 2d. I am told by another friend who has "Project Pluto: Guide" that Gum numbers are not included, the entirely of the nebula in this locale being divided into sections designated from the Lynds and Van den Bergh catalogues; with many other specific regions in an area of several degrees around the "seagull" broken down into diverse 'sub-species'. Numerous articles and photos of this object on the Net also stipulate "Gum 1", often combining the designation with IC-2177. And, of course, one already knew that the eponymous "Gum Nebula" refers to an unimanginably vast nebular complex across about 40 degrees of the southern sky, discovered by Australian astronomer Colin Gum from photographs produced in 1952. Generically, the "Gum Nebula" is often used to describe a supernova remnant expanding across the boundaries of Puppis and Vela, about a half to 2/3rds the distance to Orion nebula region, according to modern spectroscopic measurements. Gum's catalogue runs to many individual numbers; and, frustrating for me, it does not seem to turn up anywhere completely listed on on a webpage, nor in any of my computer program databases. [See update below -- the catalogue is now online!]  I have ultimately concluded that I could rely on the professional astronomer Adam Block, formerly on the staff of Kitt Peak National Observatory, who describes his image of the "seagull's head" (link given above) as comprising "a portion" of Gum 1: that's good enough for me.

On the evening of that same long Sunday, I was giving our two dogs their constitutional after twilight had set in, and cast my eyes upward to survey the bland glow of the San Jose sky, running from brownish-orange to gray-blue. I counted but a dozen stars: no more than that. It seemed almost a miracle to realize that 12 hours earlier, and just a few miles away, I had been perceiving by eye the delicate variations in part of this gigantic faint cloud of star-stuff!

Update: The same organization producting the Sharpless Catalogue online has now added the Gum Catalogue, which I discovered in November 2007. Nebula Gum 1 is discussed in detail on this webpage; you may also be interested in the Gum 1 page of the Deep Sky Browser.

Wide Finder Chart        0.5 to 2d Eyepiece View Chart: upright, correct

Yawn. It tires one out to spend two or three hours with an accurate GOTO telescope, flitting from one galaxy to the next. When I first got my Celestron NexStar 11 telescope, I had trouble using computer control (recounted in a companion article about astro software problems), so my practice for the first three or four months was to set out the Sky Atlas 2000, survey the objects in a region of sky, and then call them up from the database built into the scope. I found in short order that, conditions permitting at "the site" -- namely, at least a little ground fog or a temperature inversion at lower elevations -- I could find just about every object on the page, save only the widest angle faint nebulae that could not be contained in the eyepiece field of my instrument. NGC galaxies weren't particularly difficult; they were all discovered visually and my instrument could yield them up to me. IC galaxies: well, they were a bigger challenge. Some of them go down to 15th magnitude, and if I was lucky, and had a good sky, I gradually came to have less and less difficulty confirming an observation of the ones I sought. But, after viewing hundreds of these extremely tiny, faint blobs, one becomes a bit jaded. How faint could I go?

At last I had my software program working right, pointing my scope (after some careful calibration against reference stars) within a window of 2 to 4 arcminutes of a desired object. So, I started to go after the fainter galaxies that escaped the surveys that comprised the Index Catalogue.

One assumes that an 11-inch aperture scope, which has a published manufacturer's stellar magnitude limiting rating of 14.7, isn't likely to go 'deeper' than 13-14th magnitude on extended objects that have their light spread out. But I soon realized that I could get a full magnitude deeper even on galaxies, than the Celestron "limit". I was seeing objects that were dimmer than 15th magnitude!

The next challenge required that I reset the parameters of my star chart software. In order to keep the screen displays from filling up with objects in a jumble, I had cut off the objects fainter than 15th magnitude. But, no more: I was seeing objects in the eyepiece that were not plotted on my computer screen! So, the magnitude limit went lower...15.4, then 15.6, then 16. Surely that's low enough, right? No! I finally set it to 17, but the display was so cluttered with galaxy icons that I could not stand it, and backed off to 16.5. And right away, I got to the limit of that setting!

On the morning of 29 October 2006, which was not even a particularly good observing night -- there being more light pollution than I wish to experience, with less fog below me than optimal -- I found a nice eyepiece field that had three galaxies brighter than 17th magnitude, in Triangulum (a constellation to which I had previously paid little attention.) In fact, I was working my way through it, getting one galaxy after another without fail. This particular eyepiece field -- about a half-degree width as shown in the image from the POSS-1 blue plate above, and in the finder chart below -- has some faint galaxies that were a challenge to the 48" Schmidt telescope at Palomar, and which I know I'll never see. But there is also a very narrow edge-on galaxy that piqued my curiosity: UGC 1499, which was rated in the PGC database used by TheSky 6 at 16.5 magnitude; on the website of Rob Gatter, in the lists called up by his Deep Sky Object Cross-Reference Data For LX200 Users (data in the Meade LX200 telescope database for Messier, NGC, IC, and UGC objects by number) I found that UGC 1499 is specified as being 16.3 magnitude: not a great difference and possibly not immediately apparent by eye; let us just agree that it is considerably fainter than magnitude 16.

As you can see in the Palomar image above, this UGC galaxy is a relatively 'tiny' thing: 1 by 0.3 arcminutes. In looking around on the net, I haven't even found any kind of information other than it's a spiral galaxy with the alternative designation PGC 07666: an obscure one of concern only to professional astronomers. A better picture of it may be found here, shown in the same field with the face-on spiral NGC 783.

My observing notes for the morning indicate that I found NGC 785 to be "good" and clearly seen with a 15mm (187x) and a 12.5mm ocular (224x); NGC-783 was "a large oval glow, with 2 faint stars opposite and equidistant from the nucleus", observed in my 12.5 mm Lanthanum eyepiece. I made no mention of perceiving the spiral arms; they may not be resolvable with an 11-inch aperture, at least by me.

The real challenge object is UGC-1499. I scribbled excitedly, "I got it! 7.5 mm Lanthanum eyepiece (373x); approx. 2 min. from a c.13th mag star." When I looked that up on the planetarium program, the star was GSC 2312:833, at 13.6 magnitude. The galaxy required a certain amount of determination to be able to perceive, using averted vision, changing oculars, and bumping the telescope slightly, after carefully correlating my eyepiece star field with the plot on the computer screen. But, it was confirmed. As has been my practice, I went back to the field several minutes later, and once again found it. I do hope that users of scopes with at least 10" aperture will try for all three galaxies in this nice eyepiece field! And, if you use a star chart computer program, be sure to turn off "conflicting catalogues" or you may get overlapping or offset plots of the two NGC galaxies, as I did with two different programs until I eliminated the 'wrong' obsolete catalogues from the onscreen display. Since almost any decent star chart program or atlas will plot at least the relatively bright galaxy NGC-783, I am supplying below only the eyepiece field chart.

0.5d Eyepiece View Chart: upright, correct

Now that I've devoted a significant amount of study to this item, I've included it here though it's by no means a "challenge object" that should be particularly difficult to see. It might even be quite interesting in a 6-inch scope. NGC-1491 is variously described as an emission, or a reflection-emission nebula; perhaps even a "star burst region". It was such a startlingly beautiful sight in my 10" f/4.7 Dob, on the late night of November 14, 2006, that I was amazed that could not recall seeing it back in the early 1990s when studying objects that were included in my "Eyepiece" program. Indeed, my impressions on this recent occasion were much more vivid than before: I am surprised that one is unlikely to find it discussed in observing guides. I would consider this a "must see" object for any deep-sky lover!

A splendid color rendering, done with a 16 inch aperture Ritchey and credited to Jackson and Rena Smith with Adam Block of NOAO, is found here, wherein it is described as being "an emission nebula found in the constellation of Perseus. This particular nebula has an 11th magnitude star in its center. The 'reddish' color of this object indicates that it is heavily composed of HII. Note how the central star is 'blowing' a bubble in the gas that immediately surrounds it. The winds from this star are so energetic that they are breaking up the nebula to left of it in this picture."

Perhaps even a bit more detail is visible in this larger scaled image done with a webcam and a Celestron 8" scope, by Jim Thommes, whose RGB exposures were augmented by an H-alpha component: the faint outlying hydrogen luminosity, in red here, was just barely visible to me by eye (as pale gray, in the shorter wavelength of H-beta.) A late-generation POSS digital picture was used to illustrate this webpage, by the East Valley Astronomy Club of Mesa, Arizona, which contains a useful finder chart. In the deep, detailed exposure displayed there, even more faint nebulosity is visible than in the color images; very little of this was even suspected by me from the view in a 10" scope at "my site".

According to the NGC, 1491 was discovered by William Herschel in 1790: his reported position is the center of the nebula, a bright spot 1.5' west of GSC 3339:339 (magnitude 10.8) though the "resolver" for the Digital Sky Survey brings up a view centered precisely on the star, with the nebula fanning off to the right of center. I have cropped and readjusted this picture and show, above left, about an 8-minute field centered on "Herschel's spot"; in addition, I took the liberty of correcting a defect in the original picture: a sharp dark line across almost the entire width of the field depicted.

That bright spot was extremely evident to my eye, more so than in a photo. My observing notes (edited and expanded a bit from my scratchings in the dark) state: "Very bright nebula, easily seen with 21mm Stratus ocular (4mm exit pupil, 57x) and quite easy to find, star hopping from 47-Lambda Persei. The nebula is just under 2d from the bright large cluster NGC 1528, which will show up clearly in one's finderscope...All nebular filters help, but the O-III filter was effective in my scope only up to 80x (3mm exit pupil); with a 6mm Expanse ocular (200x) using a general light pollution reduction filter -- Orion 'Skyglow' model -- I could see all the details described in Strong & Sinnott's Sky Atlas 2000 Companion, to wit: 'Small and very bright; has a fainter, extended envelope (about 25'). Two strong wisps form a narrow V shape with the NNE end open.' I perceive that the nebulosity covers an area 2/3rds of the way around an ~11M star, with more faint nebulosity extending out, visible with 9mm and 12.5mm oculars, using the UltraBlock filter."

So, here is at least one deep-sky object that looks remarkably similar, by eye -- in a not particularly dark sky, using a 10" scope -- to a large professional telescope's photograph, with fascinating subtle details worth studying carefully. The 'bright spot' -- just to the right of absolute center in the POSS-1 blue plate image given in this article -- was exceptionally discrete, almost stellar up to 200x, with more vivid contrast than in the picture. However, the distinct "fingers" of nebulosity were much more diffuse, being detectable as a variation of glow minus the sharp boundaries.

A very interesting discussion on the morphology and diameter of the object, and conflicting catalogue reports, is found in the concluding part of this article by David Kingsley.

This is a definite "challenge object"! Jan Wisniewski's web article has a CCD image that is not too far from the faintness of this planetary nebula as seen by eye using my 10 inch scope, though the difference perceived was that (a) I did not see a ring but a fairly evenly illuminated disk; and (b) the central star was not perceived with absolute certainty, despite my most diligent efforts. A finder chart is included by Jan, showing also the much easier and larger clusters and nebulae, close-by IC 1848 and IC 1805, as well as the famous "Double Cluster" (NGC 994/869.) My only caveat about this chart is that the planetary is but a "tiny dot" on the same scale of the chart, not the "big purple ball" as depicted.

Despite its proximity to the Double Cluster, I found it a very tedious, frustrating star hop to get to the exact spot of the planetary. Only 28 degrees from the north celestial pole, it was overhead at the time I hunted, making it extremely difficult to find with a large, heavy Dob. I suspect that I was only able to acquire the field because of careful correlation that I struggled to attain using my upright-correct 9 power finderscope, and the first chart of the Sky Atlas 2000: it would have been a snap to get, using my GOTO C-11, but during early morning of 15 November 2006, the humidity at 3400 feet altitude was nearly 100%, not a good weather condition for a scope with an exposed front corrector plate: since the dewpoint and ambient temperature were precisely equal, even a long dewshield probably wouldn't have been effective. So, I chose to use the Dob meaning that hunting for faint, tiny objects might occupy most of my entire session, rather than observing them.

Nevertheless, along the way I was able to enjoy a number of clusters, including the impressively bright and 'busy' Stock 23, and Trumpler 2. When I found the proper locale, I found it necessary to zero in between two triangles of stars, slightly offset from each other: the planetary was located, at last, as a very, very dim patch, slightly less than 2 arcminutes from a 10th magnitude star (GSC 4049:1189, or BD + 60 0631.) I must have passed over it nearly a dozen times: though prepared to find a "blob" of 35 arcseconds' diameter, I was not certain how bright or faint it would be, since the surface brightness of planetary nebulae is rather unpredictable, using merely the conventional visual magnitude estimates found in many catalogues. The Sky Atlas 2000 Companion by Strong and Sinnott rates it as being 13.2 magnitude, which -- given its very small diameter -- should mean a fairly detectable surface brightness. But, not so! It is exceedingly dim in a 10-inch aperture instrument. I finally abandoned using my 'normal' search ocular -- a widefield Stratus 21mm (57x) -- and changed to a 15mm (80x): eventually, the dim disk was visible as I slowly scanned across the stars nearby. Trying my UltraBlock and O-III filters with various eyepieces, I decided that both achieved a slight enhancement of contrast though only at magnifications ranging from 80x (3.2mm exit pupil) to 96x (2.6mm e.p.) After many experiments I decided that for this scope and sky condition, my best results were with the O-III filter and a 12.5mm ocular (96x); but the planetary's pale disk was discernible without a filter, a shade of brightness just above the dark gray sky background glow.

The POSS-1 blue plate, used here for the illustration, depicts a nice annulus: a miniature version of the Ring nebula. I did not get a hint of this, under my conditions of observation. Unfortunately, the object being a circumpolar one, it is always located in the brightest central lobe of the light dome from San Jose, from "my site" in the Santa Cruz mountains. And, there was not much fog or cloudy weather low in the Santa Clara valley skies to cut out the streetlight glow. That I saw it at all was surprising. I hope to study it more closely in drier weather with the C-11, and in a darker sky: perhaps the 'ring' will at last be evident to my eye.

An obsession of planetary nebula observers is to pick up the faint central stars that excite the outwardly- expanding gas clouds. As usual, I tried; but in fifteen or twenty minutes of struggling to keep repositioning my Dob, I did not find the central star the slightest bit obvious. My practice in observing new objects is to go back to them later, during the session, to see if I'd learned how to find them and what the nearby star field looked like; and so, thirty minutes later, I left another object and returned to the position of IC-289, which now was quickly obtained. I got out my highest magnifying eyepiece -- a 3.7 mm Orion "Epic" ED-glass ocular -- and popped it into the scope, focusing as quickly as possible before the object left the field. I stared intently and had some significantly greater success, now at 324x (with only a 10 arcminute diameter field of view), soon starting to perceive "sparkles" across the disk of the nebula, blinking in and out with the slightly varying seeing conditions. I wrote down that two or three of these sparkles, in different positions including perhaps the center of the disk (possibly traces of the central star, plus one or two that appear near the periphery of the annulus) were discerned as I watched for a few minutes. The central star is generally rated at 15.9 magnitude or slightly fainter: my experiments indicate that I certainly can see such a star in my C-11, though this was the very first time I suspected that it had been done also with my 10-inch aperture telescope.

As to other details that amateur observers may detect, "Skyhound" Greg Crinklaw reports finding an interesting blinking effect of the inner and outer halos of the nebula, using his 18 inch aperture scope -- but he does NOT report seeing the central star (though he observes in pristine, dark New Mexico skies.) His eyepiece depiction, about a degree in diameter, may be helpful if you don't have a very precise GOTO scope (but just make sure you don't expect the little 'bright green dot' in the onscreen plot to show up that way in your eyepiece!)

A nice color image with a 16 inch Ritchey shows the interesting detail of the outer halo, not clearly depicted in the monochrome POSS image, above, done decades earlier.

• Link to Jaakko Saloranta's observation by means of an 8" Dobsonian scope.

Wow: what an object! This is a spectacular nebula, which -- though small in diameter at 5-1/2 by 3 arcminutes -- leapt out of my eyepiece as soon as I got my scope onto the field, easily found by star hopping about 5 degrees northwest from Rigel, a familiar star in the hunter asterism of the constellation of Orion. I have to confess that I knew nothing about this wonderful object before trying to find it on the morning of 15 November 2006. As I have said here before, I don't believe in thoroughly and exhaustively planning an observing session, primarily because at "my site" there are light domes from several directions that are variably illuminated during night-time as Pacific coast fog, and low clouds, drift below my mountain top location. Sometimes a certain region of the sky will be amazingly dark, though 60 to 90 degrees away, a nasty streetlight glow will wash out faint detail.

On this particular morn, I suddenly noticed that as Orion reached the meridian, shortly before Moonrise, the faint Milky Way became evident in the darker sky that had resulted from the loss of the usual Santa Cruz lights, which had "winked out". Resisting the impulse to look at M-42, M-43, the Horsehead, or the usual suspects I'd seen for decades, I struck out into unexplored territory. Though it was darker than usual, I failed to turn up any trace of the Witch's Head nebula or Barnard's Loop, discussed above (and visible only in the very darkest skies.) But there were a number of galaxies to the west of the "hunter" that were plotted in the Sky Atlas 2000, and I went for them, finding rather rapidly the faint and 'tiny' NGC-1726 and NGC-1700; and then sought NGC-1788, merely a small green square icon on the chart. What a shock!

The nebula is simply a staggering sight, especially after struggling to see two galaxies in the brightness range of 13-14th magnitude. NGC-1788 is a reflection nebula -- indeed, some sources also suggest that it is an emission object, glowing in the wavelengths of hydrogen -- that I found to be enhanced considerably by using the Orion "Skyglow" general purpose light pollution reduction filter, with exit pupils ranging from 3.2 mm (80x) to 1.9 mm (133x) using my 15 and 9 mm oculars, respectively. My observing notes indicate that I found a very bright, small spot much narrower than an arcminute in diameter in the expanse of nebular glow; an examination of the detailed photos referenced in links given here would indicate that the bright patch is surely very dense reflective glow around one of the stars involved.

Try as I may, I could not see an absolutely definitive, clear boundary to the dark region, Lynds 1616, on the southwestern perimeter. I even experimented with O-III and Hydrogen-Beta filters, to try to darken the background. The latter did seem to show some vague indication of a drop-off in glow that was somewhat darker than the norm in the region. But, did I 'see' it because I knew it was there, having noticed the indication on my star chart and taking a hint from the description I'd read in the Sky Atlas 2000 Companion? Or was it really there, obvious enough to detect with no preconceptions? I am not sure. A somewhat darker sky, and my larger and more efficient C-11 scope, might resolve my uncertainty.

This web page article shows very clearly, in an excellent monochrome picture, the flanking dark region Lynds 1616. However, another and even more stunning image, done in color by Jim Misti with Robert Gendler's computer processing, reveals details that surely no human eye could ever perceive with any telescope, no matter the aperture size. The rich colors and detail of earth-based amateur pictures like this still take my breath away (remembering as I do the heyday of film astrophotography in the 1980s-90s, and the limits of that medium.) Only slightly less impressive is a fine picture taken by Jim Thommes with a webcam attached to an f/5 Celestron 8 inch aperture scope in the very dark sky of the Anza Borrego Desert in California.

The East Valley Astronomy Club website has an short but helpful article about the nebula, including a finder chart. Find... look... and enjoy!

The Sharpless catalogue of emission (H-II) regions is discussed above, in the section about Sh 2-101. While looking for objects in nearby Cassiopeia at "the site", just after midnight on 15 November 2006, I passed from NGC-1491 nothward, noting a large wavy green isophote plotted on chart 1 of the Sky Atlas 2000, labelled Sh2-205. Knowing from experience that these objects are very pale, if seen at all in an eyepiece view, and realizing that the farthest extent of the wider boundary traced a diameter of nearly 2 degrees, I felt that it might be impossible to see the object at all, even in the fairly wide potential field of my "fast" f/4.7 Dob. At least the light-gathering of the 10-inch mirror might give me a fighting chance...

But first, a digression. To download a POSS image, I obtained the central coordinates that resolve the Digitized Sky Survey's position for the nebula. The maximum field I could download was only 1 degree, half the width of the entire object. Try as I might, though, every image I obtained seemed faint and indistinct: the older POSS survey pictures, even with red plates, barely showed anything but stars. Obtaining a full degree diameter picture from the UK survey, I was at last able to see something of the nebula; but amateur photos show more.

George Greaney's wonderful website of his astronomical images includes a superb rendering here (where I learned incidentally that this object is nicknamed the "Peanut" nebula due to its distinctive shape.) George still uses film, and does exceptional wide field color photography, which he masterfully processes on his computer. This picture is from his gallery of images done with a six-inch Astrophysics f/7 EDF Refractor. There is no mistaking the vivid red hydrogen-alpha wavelength light of the excited atomic hydrogen gas in this vast swatch of sky glow.

Now, as I observed with my telescope, I had no preconception of this object, not having seen any pictures. What I perceived when carefully sweeping across the field, using low powers aided by an Orion UltraBlock filter at the largest exit pupils practical for my scope (5-6mm with 1.25" barrel eyepieces), was a 'normal' star field. I tried again and again, and finally gave up on this combination of equipment. Was my sky background glow too high, from distant San Jose photons? In such cases I often try a more efficient O-III filter: and, yes, it helped, but only slightly. Finally, I decided to attempt an unorthodox experiment. The Sharpless nebulae glow from excited hydrogen, right? Certainly. And atomic hydrogen radiates not only the reddish h-alpha wavelength at 656.3 nanometers, but also the shorter, greenish h-beta (486.1 nm.) Why not try the Hydrogen-beta filter? And try it I did, finding that, at last, some distinct results were obtained: now, the nebula was just barely visible, using one of my favorite oculars, a high-transmission Orion "Ultrascopic" 25 mm eyepiece, which benefits from excellent coatings. In some previous experiments I found that this eyepiece made all the difference, with objects at the threshold of detection.

In my 10-inch Dob, that ocular yields 48x with an exit pupil of 5.3mm: almost ideal for the H-beta filter. The resulting field of view was slightly more than 1 degree, comparable to the area shown in the POSS plate presented above. My observing notes state that I found the nebulosity brightest in the center, in two "clumps" between the brightest stars. This is sufficiently vague that when I produced my eyepiece finder chart, below, it was hard to remember precisely where the glow was most distinct. Believe me, in the sky at "my site" the detail is hard to retain in memory with absolute certainty. The picture at the right (a reversed, inverted image as seen in a Newtonian reflector scope) illustrates my attempt to process the central region of the Palomar picture to begin to resemble the faint breath of hydrogen gas glow that I saw after optimizing my viewing conditions: even then, it's still TOO BRIGHT as I had to make sure it would show up at all on most computer screens!

A last word, to those of you who almost never find a use for your Hydrogen-beta "Horsehead" filter: here's another object for it.

2d Eyepiece View Chart: upright, reversed

This object was observed -- if I can use such a definitive statement! -- during a session that I had undertaken merely as a sort of worst-case test of "my site". The day of America's celebration of Thanksgiving, Thursday 23 November 2006, was brilliantly sunny here in the San Francisco bay area; but this was only a brief respite from ugly, cloudy, miserable weather that we'd experienced for more than a week. I doubted that any useful observing could be done around the time of November's new Moon, although the forecasters oddly predicted "clear skies" for this particular holiday. I was mystified by that, as an examination of the Pacific coast satellite views on the GOES page -- see here for the current daily image -- showed clouds, nothing but clouds, for thousands of miles out toward Hawaii and thence to the orient: day after day. But when I rose on Thursday, this gloom had parted, and I eagerly looked forward to the chance to use my telescope (while other 'sane' people are snoozing off their turkey and stuffing in familiar warmth and comfort.) But the actual measurements of temperature, humidity, and wind at the mountain weather station a thousand feet below "my site" showed a worrisome state of affairs: the previous night's winds had reached gusts of 35 mph, with the dew point ominously high. I wondered if the dewshield for my C-11 would be adequate; and it surely would upset the stability of my scope in high winds. So, the "backup" telescope had to be used, my 10" Dob.

I reckoned that my cold weather clothes -- rarely needed in full regalia, 9/10ths of the year here in California -- would be absolutely necessary: and then some! So I duly donned two pairs of socks, three pairs of pants, three shirts covered by a sweatshirt, two knit caps (one ski mask covering most of my head, the other perched on top), my canvas eyepiece jacket, my orange jumpsuit, my warm suede jacket, and my outer cold weather coat with goose down insulation: looking like a comical village idiot, though at least a warm one. The night was so inauspicious for observing, in the driving wind, that a solicitous stranger pulled his car over on the winding mountain road as I struggled into the last of my habiliments. He was certain that I must have had a breakdown but I assured him that I was actually intending to observe with my scope. Shaking his head in amazement, he drove on...

"This night has got to pay off, or it's going to be a total disaster", I muttered to myself while trying to keep the Sky Atlas 2000 from blowing away. I had grown sufficiently gloomy about the success of this operation as the day drew toward night that I had not made much preparation, deciding only to go through the objects in the December 2006 installment of Sue French's column "Deep Sky Wonders" in Sky & Telescope: a survey of some interesting objects near Deneb Kaitos, the bright star in the lower right hand corner of the asterism marking the constellation of Cetus, the Whale. As I waited for Cetus to be better positioned, between the light domes from Hollister/Watsonville, and Santa Cruz, I looked in a desultory fashion at a few other objects, each one a tremendous struggle to acquire with the wind stinging my face and causing my sinuses to drip, my head to ache, and my fingers to feel frozen stiff. Finally, I tackled the seven objects chosen in Sue's article: with my GOTO C-11, these could be tossed off in ten minutes' time were I so inclined do to that kind of 'observing'; but with the wind chill factor lowering the 38 degree external temperature to an experience similar to about 15 degrees above zero, my faculties were sorely diminished, and getting each object in the field of view was taking many times longer than normal.

Luckily I had already spent several earlier sessions in observing the Wolf-Melotte-Lund dwarf galaxy, discussed on page 1. This difficult object out of the way, I could try for some old familiar ones -- including the spectacular, bright, and large galaxy NGC-253, which shows up in one's finderscope, and the fantastic planetary nebula NGC-246: both seen now, but not in 'their glory', for the night was not only windy, but light polluted in the extreme. A total lack of fog and clouds and haze below me allowed the lights from the communities all around the Santa Cruz mountains to gleam upwards, unimpeded. I have rarely seen so much light from the large shopping malls in Gilroy: a blight to me while beckoning "normal" people to start their Christmas shopping frenzy that very night (I listened to the radio and heard commercial after commercial announcing Thanksgiving eve hours to midnight or later...EVERY darned light in the valleys below must have been turned on for the occasion, along with Kliegl light beacons. There were even more airplanes than usual.) So, NGC-253, though recognizable, was but a pitiful, pale caricature of the spectacle it is under better conditions.

It was with sinking heart that I moved the telescope upward in altitude to try for the highest object in Sue's list: the galaxy IC-1613. I had not recalled observing it before, and had no prejudices. But, being an IC object, it would surely be dim (discovered by photography and not visually: it turns out that this was a good assumption, as Max Wolf found it on a plate he took in 1906.) And since it has "huge" diameter, measured from our Earthly vantage point as subtending an angle that spans about half the Moon's diameter, it would have a low surface brightness. I sighed, expecting my quest to be in vain: the worst possible circumstances for trying to find the most difficult kind of object.

But, no! As so often seems to occur, surprises happen to convince one it was worth the effort. Sue French described the galaxy as being "elusive", a "little smudge" barely seen in her excellent, high contrast refractor. And she describes her own site as being a rural location. I tested the stars I could see, unaided, in the area and found that I was having difficulty holding with direct vision stars in the range of 4.8 to 5.2 magnitude. But, my own eye's response, through old glasses, is not the same as that of a youngster with acute vision. Through a telescope, however, I can easily see the faintest stuff that others claim to be "challenging" or "difficult". So, when I had acquired the star field near IC-1613, brightly festooned in the eyepiece from the light of 7th-magnitude SAO 109653, a few arcminutes outside the periphery of the galaxy, I knew I'd have to be patient and not give up immediately. As I used the techniques that help me see such large diameter faint objects, gradually "nothing" turned into "something"...but what a vague, barely perceived something! I had no pictures or laptop computer with me for further information, so had to go by the clues in Sue's column. Because I have carefully determined the true fields of my eyepieces, I knew what the maximum diameter proportion of the object would be -- ideally -- at different magnifications. One expects to find that in real experience, a galaxy will often seem to occupy less than half the catalogued plot-area. But IC-1613 is so vague, tenuous, and irregular that there was no perceptible boundary; indeed, it seemed to me to resemble more a wavy and inconsistent nebula than a galaxy. That is, if I saw anything at all.

I decided that with this much milky, bluish-gray light pollution in the background, I'd need to increase the contrast. But doing so by merely stepping up the magnification would be inappropriate, spreading the galaxy too thin in a narrow eyepiece field. So I experimented instead with a small range of ocular focal lengths, and with my Orion "Skyglow" general-purpose light pollution filter.

There was recently a rambling discussion and debate about the usefulness of such filters on the newsgroup sci.astro.amateur, some people asserting that they are a waste of money. Their action is subtle to visual observers, though photographers or digital imagers get enormous benefit (as sky fogging is hugely reduced.) Some quite experienced observers dismissed the filter type altogether. I don't have this view, as I argued in a post to the discussion thread. I can only reinforce those opinions based on my tests using IC-1613: for by using the Skyglow filter and my Orion "Ultrascopic" 25 mm ocular (with excellent high transmission coatings and lens edge blackening to improve contrast, which really work!) I was able at last to be certain that I was viewing the galaxy, not merely 'imagining' it. I now had the distinct feeling that IC-1613 was similar in 'texture' to WLM, or Barnard's Galaxy NGC-6822 (both discussed above): close-by objects that have certain features that are somewhat more distinct than mere amorphous glow, rather than the bland pale light of more distant galaxies. I wish that the sky contrast could have permitted more critical examination on this occasion, but nevertheless I felt that there was a certain variation in brightness across the extent of the galaxy's axes, and suspect that I could almost detect a specific discrete irregularity that I later verified by examining professional pictures, such as this spectacular, resolved color image of the galaxy, done by the GALEX Orbiter telescope, on a JPL webpage.

Sue French reports seeing "a distinctly brighter patch in the northeastern part of the galaxy". I tried to confirm that, with some ambiguous results. I had the sensation of variability in brightness, but since the magnification I used was either 48x (65 arcmin. FOV) or 80x (50 arcmin. FOV) with my 25mm Ultrascopic and 15mm Expanse oculars, respectively, the star images were perforce small and one could mistake very faint ones, closely spaced, for irregular glow. I have tried to use processing to modify the POSS-1 blue plate employed for the picture shown above at the top of this object's discussion (a field diameter of about 22 arcminutes) in the simulation of my eyepiece experience depicted here in this paragraph (an inverted, reversed view as seen in my Newtonian reflector scope.) It seems to me, upon consideration, that under my conditions, the brightest spot was dead center (or just to the right of it) in this little thumbnail image, which does not seem to correspond to Sue's perception. Is this due to my poor sky conditions; my eyesight; a different scope and exit pupil? One cannot answer definitively.

As usual, the enjoyment of this very challenging object under adverse conditions confirms my belief that one can often have delightful experiences even in the most inauspicious observing sessions. Finally, one should note that the dwarf galaxy itself is given the rather elaborate type description "IAB(s)m V"; one learns from a web search that this means that it is an irregular one of a certain subtype designated by Gérard Henri de Vaucouleurs. As described in the appropriate section of an article in the "Near-Infrared Galaxy Morphology Atlas" by T.H. Jarrett:

"Finally, irregular galaxies (Irr) may include dwarfs (although we make a distinction, see above), peculiar (Pec), interacting, merger and 'magellanic cloud' (SBm; Im) versions (e.g., de Vaucouleurs & Freeman 1972). Irregulars are usually barred, IB, and 's' shaped, I(s). In general, galaxies that are not classified as elliptical or spiral type may be lumped into this disparate group, even though some may be physically unrelated."

Just how dim this object is when acquired not by a huge observatory camera but by typical amateur equipment can be judged from a CCD image taken by Naoyuki Kurita using a 10" aperture Meade SCT: it's distinctly possible that both Sue French, and I, have discerned more by eye.

Addendum: Perhaps I may be so bold as to quote Sue French's reaction to my difficulty with California winter chill: "I had to smile at your reference to cold weather. I observe here at minus 15º F, not taking wind chill into account. I have a permanent red spot on my cheek from one night when my face welded itself to the side of a telescope."   Well, Sue: it's all relative, isn't it? 22 years ago I observed with Don Machholz and Rich Page one December night near Auburn, California in the Sierra foothills: and Rich's eyepiece froze to his moustache. As a California resident since 1961, I've quite forgotten my youthful winters in Iowa. A decade ago, I regularly observed at "my site" when the temperature was in the twenties, but did so on calm nights. Can my aging blood handle it now? We'll see...

Update, Sept. 2007: I have also been able to see the galaxy IC 1613 with my new Orion 4.7 inch aperture refractor; an observation report and sketch are included as part of my test of the telescope, which is found here in this blog report. Interestingly, the night was so transparent and the sky so dark that I could see traces of the galaxy in the 50 mm finder I had attached to the scope (also documented in a sketch.)

My earlier discussion of the observing session on Thanksgiving night, 2006, regarding galaxy IC-1613, explains the abysmal conditions I struggled to overcome during my attempt to cover the objects discussed in the December 2006 "Deep Sky Wonders" column by Sue French in Sky & Telescope, and need not be repeated other than to say that too much wind and light pollution diminished my results. As such, I was rather surprised to find that the marvelous planetary nebula NGC-246 was so wonderfully seen in my 10" Dob, though admittedly it did not match the view in a truly dark sky, since I had difficulty holding by unaided eye the nearby stars Phi¹ and Phi² -- 4.9 and 5.2 magnitude, respectively -- and could not even see Phi³ and Phi⁴ (5.5 and 5.8) by naked eye.

Furthermore, this is definitely not a "challenge" object, as it can be studied with a 4 or 5 inch aperture telescope, and I even had the impression that it was a definitely perceptible "speck" in my 9x50 finderscope. But, the goal is not merely to see the most evanescent above-threshold perception of an object, but to get a really definite impression of it: identifiable with some recognized detail that can be confirmed in a picture or from others' observations. And that's exactly what I found when I put my O-III filter on the threads of the barrel of my 15mm focal length "Expanse" ocular (which yields in my particular scope a FOV of about 50 arcminutes, at an exit pupil of 3.2 mm -- within the useful operating range of the filter -- and with a magnification of 80x.) To my surprise, since the planetary nebula was only barely visible as a ghostly breath without it, the filter caused an almost shocking improvement: much more than I generally expect. Not only did the sky background dim from an ugly intrusive blue-gray to a deep near-black; but also most of the brighter stars were still visible. And the nebula itself: wow! Now, it had a sharp defined edge, and distinctive ovoid, but slightly "squashed", shape: like a fat olive. Across the entire face of the nebula was milky, distinct nebulosity; and at least the same stars as shown in the POSS2/UK blue plate picture, above, shone through. The 11.78 magnitude central star was crisply and steadily visible. I wrote, with emphasis, "Like a photo!" in my observing logbook.

Actually, with later reference to various pictures on the Net, it was better in some respects than certain images, which do not convey the extent of how much of the nebulosity is visible against the sky background when the filter is used. For instance: in this image by Jeff Cremer and Adam Block using a 20" Ritchey, one cannot discern the pale glow across the full diameter although some of the details of the overlapping shells are shown in their colorful delicacy. Even in this utterly spectacular picture by Travis Rector (Univ. of Alaska) using the Gemini South telescope in Chili shows only more fine detail but not all of the glow that was visible by eye (in the doubly ionized oxygen wavelength near 500 nanometers, the narrow region of light passed without attenuation by the filter.)

Those observers who like to search for it with their own telescopes will surely benefit from "Skyhound" Greg Crinklaw's NGC-246 webpage, including a "finder" aid: a simulated image intending to illustrate the results in a typical 6 inch scope at 50x, based on Greg's own 6" f/8 reflector. He comments on its appearance in his huge 18" aperture Dob, saying "Not much sign of structure except for a rather strange appearance -- more of an impression -- that I can only describe as eerie." I have of course had better views of NGC-246, years ago in dark skies both at "my site" when fog filled in the valleys below me, using a scope nearly as big as Greg's, and down south on the central California coast, away from large cities. Yet, on a night when winds howled around me and my fingers were frozen by temperatures in the thirties, this was a thrill that made the struggle seem worthwhile, and made me forget the comforts of a post-prandial Thanksgiving snooze that no doubt hundreds of thousands of people below my mountaintop venue were enjoying. Sometimes, even a turkey leg's succulence can't compete with the joys of viewing planetary nebulae!

I did not find this a particularly interesting object; the challenge was merely to find and examine it since many advanced observers obviously consider it worth acquiring. J320 is a bipolar planetary nebula, as described in the appropriate section of this Sky & Telescope web article, where it is included in a category of items that are "so small that they only grudgingly yield detail and texture to the trained eye at high power." Apparently J320 had a big grudge against me, the morning I last looked at it with my C-11 at "the site" during a very fine session with exceptional seeing and clarity, and enough low elevation fog to cut light pollution significantly (on 29 October 2006.) For though this object was found rather quickly by means of careful calibration of my C-11 GOTO positioning against the plot in my laptop computer's planetarium program, my logbook records only that I found it "pretty bright, much fuzzier than a star. Used O-III filter which helps identification." Despite my use of high magnifications well above 300x, I did not record discerning the central "engine" that excites the expanding gas cloud, which happens to be a 14.4 magnitude star. The slightly oblong fuzz-patch, about all the I could make of this object, does appear significantly brighter than the two stars in the range from 12th to nearly 13th magnitude that are within one to two arcminutes' distance. According to the helpful resource provided by Professor B. Mauclaire -- the Planetary Nebula Finder Page -- the surface brightness of this 11 x 8 arcsecond object is very high: 7.77 magnitude per square unit of area, quite a contrast with such barely-seen planetaries as the larger-diameter Abell 46 or Abell 79 that I have discussed earlier.

The POSS-1 blue plate that I employed for the 8-minute diameter picture above does not quite convey the distinctness of the object since the rich radiation of doubly ionized oxygen has 'burned in' the exposure. But this color digital image by Dr. Bruce Balick, taken with the 2.1 meter Kitt Peak telescope, reveals the delicate "ansae" (Latin for "handles", a term often used by astronomers to describe the little narrow 'extensions' from the central regions of various objects, mostly planetaries: such as the more familiar, brighter, and larger Saturn nebula.) Unfortunately, when I viewed J320 on this occasion I had not previously looked at a picture, and did not anticipate the ansae; I was not disappointed, therefore, when they did not "pop out" obviously, so I didn't struggle to discern them. This detail might well be too faint for my 11 inch aperture instrument, but I will check that again when possible.

The very experienced observer Yann Pothier also fails to describe specifically a sighting of the central star, using a 17.5" scope. And, I was particularly surprised to learn on the "Cloudy Nights" forum that Tom Trusock, advanced big-Dob user and optics expert, and author of the superb Small Wonders observing column, reported that he had not found it with his 18" scope in a dark sky, stating that "identifying it's the challenge. I'd suggest as much aperture and magnification as you can throw at it." No, Tom: that's not the solution, I'm afraid! The planetary is very bright and easily discerned, with sharp optics and good seeing, as being non-stellar. The solution is either incredibly patient triangulation and manual location in a fairly busy star field, or employing a nearly perfectly-calibrated GOTO instrument, augmented by a deep plot (either in a hard copy print-out or onscreen) using the Hubble Guidestar catalogue stars down to 15th magnitude. I can predict that since the planetary was recognizable in my 11-inch Schmidt-Cassegrain scope, it would also have been detectable with my 10" Dob, which has good, sharp optics (despite its cheap price and fast focal ratio.) But, realizing my personal clumsiness at finding such small obscurities, I might predict a half-hour of fuming and fussing to do it. This is one faint fuzzy that makes me thankful for the advancement in observing efficiency wrought by the introduction of GOTO telescopes.

After initially writing this up for the Fuzzies page, I looked back in my logbook for other objects and found that I had recorded an observation, not under the Robert Jonckhere catalogue number but with the PK designation (which is probably why I had forgotten about it) earlier, at "my site", on 10.27.06: also with the C-11. I had commented that it seemed to have "a slightly rough surfaced small disk with perhaps a slightly brighter center: do I sense also an outer halo?" (perhaps an indication that I had imperfectly seen some trace of the ansae.) This time I had used even higher magnification than the later observation discussed above in depth. I had employed my Orion Epic 3.7 mm ocular which produces a whopping 767 diameters of magnification, with a field width under 5 arcminutes: an eyepiece that is really practical for use in a long focal-length scope only if it has motor-driven tracking. Judging from this, the sky conditions must have been steadier than usual at 3400 feet elevation. This high altitude often allows me to make critical examinations of details that require expanding the object as much as possible. And yet, the power is only about 69 diameters per inch of aperture, within the range that some double star observers occasionally employ for discerning the narrowest angles. To use it, you MUST have great seeing, and excellent optics, or the result is merely "empty magnification" that diminishes perceptible detail.

I have prepared helper charts for J320, below. To make up the eyepiece simulation, I had use a graphic editor to fix the chart printed by my planetarium program: for, as usual, it failed to correct the disparity of separate catalogues. It showed the one single object, J320, as being two: an 11th magnitude GSC "nonstellar" object, and a PK planetary, offset by a few arcseconds. I had to erase the erroneous one in the eyepiece chart immediately below. This is one of my greatest annoyances with star chart software programs! (Needless to say, I did not perceive the galaxy PGC 16726, shown within the 30 minute central field of the chart: it is rated at 17.2 magnitude, too faint for my telescope.) Please remember that the "blue dot" representing J320 in this chart is, in reality, a very much smaller speck of light.

Wide Finder Chart        2d/0.5d Eyepiece View Chart: upright, reversed

How much trust do you have in the "great astronomers of the past"? Do you believe that they were unerring, scrupulous, absolutely cautious and careful observers, or were they simply human, with all the failings to which our species is prone?

The late nineteenth century astronomical experts and catalogue compilers had perhaps a different attitude than most of us skeptics possess today. Now, any claim is instantly doubted until corroborated and further cross-checked. At the end of the Victorian period, there was a greater trust in authority (though nothing like the veneration for, say, Aristotle that existed before the days of the renaissance.) So, when Otto Struve reported the discovery (by eye, of course) of a new nebula -- near the earlier find of a rather similar nebula by John Hind -- in the constellation of Taurus in 1868, this legendary observer and expert was trusted: especially when his discovery was confirmed by Heinrich d'Arrest (participant in the first observation of the planet Neptune), another astronomical authority of the time. The New General Catalogue awarded the object the designation "NGC-1554", one digit away from the earlier NGC-1555 for Hind's nebula, first observed in 1852. But, were Struve and d'Arrest right?

Today any diligent amateur astronomer, favored with appropriate sky conditions and even a modest instrument, can confirm John Hind's nebula (NGC-1555.) But, during a 22 year period before 1890, the nebula completely faded from sight (or, a skeptic might claim, just wasn't seen, 'if it really had ever existed at all'.) The nebula was "reclaimed" again by the eagle eyed E. E. Barnard and Sherburne Burnham after that, and has alternately faded and bloomed over the decades, brightening somewhat during the past three-quarters of a century. But, what about "Struve's nebula" (NGC-1554)? Barnard never saw it; nor was James Keeler able to photograph it with the new Crossley telescope at Lick Observatory at the end of the century.

Now, imagine that YOU are the "Dr. J. L. E. Dreyer" of today; and somebody shows you a plot of both the Hind and Struve nebulae, as illustrated above with coordinates precessed to the current date. Whom do you believe? It is really true as Dr. Harold G. Corwin holds in his scholarly work to correct the NGC, that 1554 and 1555 "are both involved with the young variable star T Tauri... among the most notorious of the nebulae found during the 19th century as they are the only nebulae certainly known to vary in brightness -- even to the point of disappearing, as NGC 1554 has done"? That is an excellent inductive solution to the 'problem' though when one notes the remarkable coincidence of the nebula's positions with respect to other stars, and their almost identical declinations (differing only by a second of arc), then a skeptic can be forgiven for wondering... especially since Struve's nebula was not found on the Palomar sky survey plates.

Corwin also notes that the invisibility of NGC 1554, Struve's alleged object, corresponds with the similar invisibility of a nebula observed by another esteemed and trusted astronomer, Guillaume Bigourdan, only once in 1890, spotted about 4 arcminutes south of T Tauri, the star that excites the gases in Hind's nebula. Burnham's discernment that the star was situated in a small nebulous cloud -- more extensive than Hind's faint swath of glow -- led to the further investigation that finally has seemed to offer a scientific explanation more powerful than "trust in authority": that the region around T Tauri (as well as the interstellar molecular-cloud atmospheres near other "T Tauri type" young, highly luminous variable stars) can become reflection nebulae; some evolve rapidly, causing the nebulae to have luminosity variations that can explain the "on again, off again" phenomena that Messrs. Hind, Struve, and d'Arrest first detected. But, in science there is often much uncertainty: so the book has probably not been completely closed on the elusive nebula of Struve: it's invisible now; could it flare up again?

I was vaguely aware of some of this history back in the late 1980's when I first saw Hind's nebula at "the site" with my 10 inch Newtonian. I did not think it was particularly troublesome; and I remember that I looked at it again in the 1990's with my 8-inch reflector: not especially difficult to do. So, I was surprised to see that Hind's Variable Nebula had turned up in a challenge object list compiled by the legendary deep-sky observer Steve Gottlieb. His article November Challenges has a succinct discussion of the advent of NGC-1555 which needs no repetition here. I found this web page a short time after my last observation of Hind's Variable Nebula, at "the site", at 4am on the sparkling clear morning of 29 November 2006, with my C-11. My own observing logbook notes that it was "a slightly fan-shaped flare off to the western side of the star" and that the UltraBlock or O-III filter helped improve contrast at a variety of exit pupil sizes and magnifications. I still had no idea that this nebula was considered a particularly "difficult" object. But even Jay Reynolds Freeman, a splendid observer, reported that it was "very faint" and only suspected without a filter, in the dark sky of California's Sierra mountain foothills: using a C-14 scope!

Perhaps if I had read all of the above, I might have had a different feeling about this observation of mine, and those that preceded it. Who knew? Not I. Now, to me, WLM is a challenge; so are any number of other Sharpless nebulae; Abell planetary disks and shells; or subtle dark nebulae. I think this sense that I had not done anything "difficult" might tend to suggest that I may be blessed with better sky conditions than I had even imagined! It also serves to indicate that one man's physiological and psychological response to certain stimulae will never exactly match another man or woman's reaction: human variability may be just as pronounced as the variability of Hind's cloud!

Incidentally, some inkling that the theory that a rather substantial nebular region may be surrounding the entire area of both the "real" NGC-1555, and the "missing" NGC-1554 (as discussed in this fascinating article about T Tauri stars on the AAVSO website) is afforded by the picture, taken from the POSS plates, that I use above to illustrate this section of my article on fuzzies. I was very much disappointed with the view of either the blue or the red plates, which did not yield much latent information even with extra digital processing. So, I composited a picture, by superimposing both plates after individually processing them. The result I obtained definitely shows something interesting in the wider area all around T Tauri; and even more glow can be brought out by more extreme processing. The "rather unconvincing coincidence of the declinations" may be a red herring: there would seem to be a LOT of gas molecules that faintly reflect, or glow, in this swirling though incredibly tenuous interstellar region. I'll just bet that old Otto was correct.

UPDATE: Cl