SOHO/Near-Sun Comet News and Views
2004 News

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This newslog will focus on sungrazing and near-sun comets, as well as any comets observed in the SOHO (Solar and Heliospheric Observatory) LASCO coronagraph images, though I will also include important news items of general interest regarding comets.



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December 28, 2004

Today I found a faintish non-group comet tracking downwards along the lefthand edge of the C2 field. Currently caught in a coronial mass ejection, (solar storm), it seems to be arcing back under the Sun (from our perspective), and may stay visible in C2 for much of tomorrow if it doesn't fade. Two other comets were also found today; Xing Gao found a faint C2 Kreutz this morning, and this evening Hua Su found a faint C3 Kreutz.

Several comets were found over Christmas weekend; Karl Battams has confirmed and numbered them. On Christmas Eve, Toni Scarmato found a relatively bright C3 Kreutz comet (SOHO-886) that grew a short tail. It wasn't seen in C2 because of a gap in images. probably Subgroup II. Toni's comet was followed, about 15 hours later, by a slightly fainter C3 comet (SOHO-888) found by Bo Zhou. It was well seen in C2, preceded by a faint Kreutz comet reported by Hua Su (SOHO-890), and followed by another faint Kreutz (SOHO-891), also found by Hua Su. Heiner Otterstedt also found a very faint C3 Kreutz comet (SOHO-889). The most interesting comet of the bunch, though, was a non-group comet (SOHO-887) found by Heiner Otterstedt near the top of the C3 field on December 24. It took a long clockwise arc around the edge of C3, becoming moderately bright and remaining visible until early on December 27, when it faded out to the lower right of the Sun.

The bright SWAN comet that passed through C3 remained well seen, though slightly faded, by the time it was last seen in the images on December 20, when LASCO was closed due to the maneuver to flip the SOHO spacecraft. The comet was recovered in the night sky on CCD images by Ken-ichi Kadota on December 26, though by then it had faded to 10th magnitude.

December 21, 2004

Karl Battams confirmed SOHO comets 881-885, the discoveries I mentioned in my previous report. Along with the confirmations, Karl wrote "Well, with just a few observing days left in 2004, we've had over 160 comet discoveries from SOHO this year alone! That's more comets than our nearest "competitor" has found in its lifetime! An incredible achievement." The bright C3 comet, C/2004 V13 (SWAN), becomes SOHO-884; Karl Battams gave joint credit to John Sachs and Michael Mattiazzo for the discovery; the most recent MPEC about the comet correctly clarifies that Mattiazzo found it in SWAN images, Sachs in the C3 images, and Hönig made the connection between the two reports.

December 20, 2004

I'm sorry I didn't get a chance to update earlier; it's been a hectic time for me. SOHO has been in a "keyhole period" for the past 10 days. The LASCO instruments are currently closed as the spacecraft is being flipped, which happens several times a year. LASCO should re-open Thursday.

A relatively bright non-Kreutz comet is slowly tracking across C3. It was first reported in C3 images by John Sachs on December 16, but is the same comet reported in SWAN images from November by Michael Mattiazzo. The comet was credited on the MPEC to Sebastian Hönig, who made the connection between the SOHO and SWAN reports and calculated a preliminary orbit.

On December 14, Brian Marsden reported in MPEC 2004-X73 that it is "eminently possible" that C/2004 V9 (SOHO), a bright Marsden comet visible in November 8 images in both C2 and C3, is identical with C/1999 J6 (SOHO), which reached perihelion on May 11, 1999. Indeed, their orbital elements look very similar, and a tentative period of 5.49 years. This all but confirms what many in the SOHO community had suspected: that the Marsden group (as well as the Kracht group) is short-period, with an average period of 5 to 6 years. In 2003, K. Ohtsuka, S. Nakano, and M. Yoshikawa published an article linking the Kracht and Marsden groups to Comet 96P/Machholz and the daylight Arietid meteor shower, that the two comet groups were in effect fragments released from 96P/Machholz at specific times in the comet's orbital evolution when its perihelion distance was at its minimum, some 4,000 years ago. They further suggested that Marsden and Kracht comets might have similar periods to 96P/Machholz (5.2 years), and that 2003-5 might see the return of comets from these groups seen starting in 1998. I had carried on a correspondence with Katsuhito Ohtsuka and David Seargent on this matter ever since I found a faint Marsden comet on August 20, 2003. David e-mailed me the next day, saying it may be the return of a Marsden from January 1998, the first of 3. He predicted another for six days later, and sure enough, Rainer Kracht found one on August 26. The third one, which would have come two days later if the periods were identical, didn't show up, though (and I thoroughly checked the images for about 10 days around that time in case one had been missed). When the orbits were finally calculated, it turns out that mine and Rainer's had orbits that were different, and maybe weren't Marsdens at all. Early this November, David told us to expect a bright Marsden comet around Christmas--the return of C/1999 J6. A week later the bright Marsden comet showed up, which we surmised was probably the return of J6. (David had estimated the period based on the August 2003 comets being the return of the January 1998 pair, and basing the period of Marsdens on that interval.) I e-mailed Brian Marsden, telling him of our suspicion, though the likely concordance was probably evident to anyone who was following the situation closely. (Brian, along with Paul Chodas, had already found that two Kracht comets from May and June, 2004 were likely returns of objects from June and July, 1998.) It's wonderful that we are presumably now seeing returns of Marsden and Kracht comets from the late 1990s. This vindicates the work of Katsuhito Ohtsuka, et al., among others.

Karl Battams found two quite faint C2 comets in delayed images of December 13. That evening, Gregg Gallina found a Fairly faint C2 Kreutz comet, his second SOHO comet and his first in a year. On December 18, Hua Su found a faint C2 comet. Finding and observing SOHO comets has been hampered by the gaps in images due to SOHO's "Keyhole" and the spacecraft's maneuver; we will miss a chance to see the bright C3 non-group comet at perihelion.

December 9, 2004

Yesterday, two new SOHO comets were found. Rainer Kracht reported a non-group comet from images of December 7; it tracked across the upper left corner of the C2 field. Later, Rob Matson found a moderately bright C2 comet in realtime images; it was also faintly visible in C3. (Rob also reported a C3 comet that is likely real, but Karl Battams says it may become an X-comet due to a data gap; there have been no new images in more than a day.) Today, Karl assigned the new comets SOHO numbers; Rainer's became SOHO-879, and Rob's, SOHO-880. My comet from December 6 is SOHO-878. Rainer's comet is his 137th, putting him just 6 comets behind Michael Oates for the all-time lead.

December 7, 2004

Yesterday, Karl Battams gave two comets SOHO numbers: My comet of December 4-5 became SOHO-877, and a previously unconfirmed C2 comet found by Bo Zhou on November 21 is SOHO-876. Bo's comet was round and faint, and quickly faded.

Last night, I found another C2 comet, which Karl Battams confirmed. It was in delayed images from earlier in the day. The comet faded rapidly, and was small and diffuse, yet visible in 12 images.

December 4, 2004

Tonight I found a C2 comet; it was round and fairly faint. It tracked almost straight upward through C2; I first found it "among the numbers", where it was partially obscured by the timestamp that's in the lower left of each image. This is my 40th SOHO comet, and 30th this year alone; I am astounded by my good fortune, and I'm somewhat at a loss to explain it. It took me more than 2 years to find my first 7 SOHO comets; I have found that many since the beginning of November. Certainly, there is some improvement in skills over time, particularly in being able to rule in/rule out possible comets and to report viable candidates quickly, to recognize the signs of a comet in its earliest stages of development, to be able to utilize both color and b/w images efficiently, and to be alert for not only Kreutz comets but also ones from other comet groups as well as sporadics. I'm sure all has contributed to my total this year, but luck has also played a significant role; there have been many comets that have become visible during the hours that I've looked for them; in past years, that hasn't always been the case.

December 3, 2004

Last night, Steve Farmer, Jr. discovered his first SOHO comet, a faint object in C3, small and round, that brightened somewhat as it approached the Sun. It showed nicely in C2, teardrop-shaped and with a bit of a tail.

Two comets were found on November 30. Rainer Kracht reported a Marsden comet in images from the previous day. It was faint, stellar in appearance, and visible as it was exiting the C2 field. Ten minutes later, Rob Matson reported a realtime Kreutz comet in C2; it was rather faint, and round.

November 28, 2004

Today, Xing Gao reported a faint C2 Kreutz comet with a hint of a tail; it was reported soon after by Maik Meyer as well.

Last week, John Bortle reported to the Yahoo Comets mailing list that Zdenek Sekanina, the renowned comet researcher who has made extensive use of SOHO comet orbital data in seeking to determine the history and fate of the Kreutz group, as well as to better understand the dynamics of cometary fragmentation, has submitted a new paper on the origins of the Kreutz group to the Astrophysical Journal . By John's description, this paper, titled "Fragmentation Hierarchy of Bright Sungrazing Comets and the Birth and Orbital Evolution of the Kreutz System, II", discusses the likelihood that many bright Kreutz sungrazers may have passed perihelion undetected through the centuries, and seeks to identify some possible early apparitions of the progenitor(s) of the Kreutz group as well as more recent candidates. In addition, Sekanina believes SOHO's Kreutz fragments to be from a filament of material bridging two major sungrazing comets, and that a slow yet steady increase in the number of Kreutz comets seen in SOHO over the years may herald the eventual arrival of a bright sungrazer, to be closely preceded by a number of especially bright SOHO comets!

Last week, Maik Meyer reported to the Yahoo Sohohunter Mailing List the naming of an asteroid after Heinrich Kreutz, the researcher of sungrazing comets after whom the Kreutz group is named. Here is the citation: (3635) Kreutz = 1981 WO1 Discovered 1981 Nov. 21 by L. Kohoutek at Calar Alto. Heinrich Carl Friedrich Kreutz (1854-1907), astronomer at the Kiel Observatory and from 1896 editor of the Astronomische Nachrichten , is renowned for his seminal three-part study of the family of bright sungrazing comets, now known as the Kreutz Group. The name was suggested by M. Meyer, B. G. Marsden and R. Kracht.

The comet I found in C3 early on November 24 developed quickly and showed a narrow, delicate tail up to about 1/3 degrees in C3 and in C2, where it was particularly well seen. Bo Zhou reported a fragment to this comet in C2; there is a bit of a brighter bulge in the righthand edge of the tail just below the nucleus, but it is unclear whether there is a second condensation there that would count as a separate comet; it'll be interesting to see how Karl rules on it.

November 24, 2004

Yesterday morning, Xavier Leprette found a comet in delayed C2 images; it was soon after reported by Hua Su. It was rather faint, small, and slightly oval. This morning Xavier found yet another faint C2 comet, in delayed images. These bring his total to 92; he should get 100 before SOHO finds its 1000th comet, sometime next year.

Last night, I found a C3 comet in realtime b/w images (my first C3 b/w find), after an image gap of about 9 hours. It had appeared rather abruptly, brightened and has developed a short tail. It will probably be well seen in C2.

November 22, 2004

This morning, Sebastian Hönig reported a C2 comet, followed shortly by Bo Zhou. It was a small, faint, and round comet, visible in about 9 positions.

November 20, 2004

On November 18, Toni Scarmato reported a very faint C3 comet, just below the Sun, which also became visible in C2. It's Toni's 12th SOHO comet, yet his first in more than 2 years. Yesterday, Rainer Kracht reported a somewhat brighter (yet still faint) C3 comet, which was soon reported also by Hua Su and Toni Scarmato. This one was also visible in C2. Karl Battams confirmed these and the two I had found, bringing the total number of SOHO comets to 867. Karl will be away on vacation for the next 10 days, so there will be no more confirmations by the SOHO team until the end of the month.

November 16, 2004

Last night, I reported a rather faint, small and round comet in C3 to the lower left of the Sun, tracking to the upper left. I wasn't sure if it was a non-group comet or a Kreutz variant (probably Subgroup II), as it came from about 15 degrees to the left of a typical Kreutz comet at this time of year. In examining the C2 images in which it appeared, it does seem to be Kreutz-related, as the comet curved gradually but steadily to the right towards the Sun's left limb as it quickly faded. A bit over an hour after I reported the comet in C3, I found a Kreutz comet in C2. It was fairly faint and round, with a hint of a tail.

The night before, Maik Meyer found a C3 comet, fairly faint and round, rather close to the Sun. He reported it to the Yahoo Sohohunter mailing list, because the main report page on the NRL/LASCO site was out for repairs; it is SOHO-863. The comet was later seen in C2. Hua Su also reported a C2 comet in two images from November 12, but because of a data gap, it's unclear whether it's real or confirmable.

November 10, 2004

This morning, when about 12 hours of images were uploaded at once, Xavier Leprette reported a Kreutz comet, about halfway to the Sun in C3 images, and already developing a short tail. It could be traced back in images almost to the edge of the C3 field. It brightened and kept its tail as it approached the Sun; there is currently a break in the image stream when the comet would have been at its best; hopefully the missing images will be uploaded before too long. [Nov. 16. The missing images came in over the weekend, and the comet was well seen in C2.]

November 9, 2004

Yesterday was a busy day for SOHO comets. Two days of delayed images were posted, starting around 9 a.m. Karl Battams reported a C3 Kreutz comet from the previous day's images; it was starlike and relatively faint. Later, it appeared as a small, brighter spot in C2. Then Heiner Otterstedt reported a non-Kreutz comet moving away from the Sun. Images from November 8 were affected by solar activity that produced aurorae in Earth's skies; this proton storm caused noise in the form of white dots to appear all over the images, making it a lot harder to detect comets. Karl Battams not only located Heiner's comet in C2 (although it was bright, it appeared rather stellar, as is typical of Marsden comets--which it turned out to be--and was hard to distinguish amid all the noise), he also reported a fainter companion preceding it by a few hours.

When I got home in the evening, I checked the images, and a bit to my surprise found a faint Kreutz comet that had no doubt been missed because of the noise from the solar storm. Then I reported a non-Kreutz comet that I saw entering the C2 field from the right, near the bottom. Although I have no doubt it was a real comet (due to its trajectory and its distinctive appearance), it was fading rapidly and only visible for sure in three images. Karl thinks it will probably end up being an X-comet (a comet believed to be real but without enough positions to calculate an orbit and make it official). Still, with the four comets that were confirmable, SOHO's total has grown to 861.

November 4, 2004

Last night, I managed to find two Kreutz comets within 40 minutes of each other, one in C2, the other in C3. While examining the C2 image from 0330 UT, Nov. 4, I noticed a small, round patch at the bottom of the field that I suspected might be a faint Kreutz comet. For 0354, only a black-and-white image was then available, but there was a spot in the correct position. I waited for one more b/w image, and then reported it. Soon after, I was looking at C3 images and saw a small, faint spot moving towards the Sun from below; it was later visible in C2 as a small, round spot, brighter than the other comet had been in C2. Based on their similar appearance, proximity (the second followed the first by 5 hours), and nearly identical trajectories, I suspect that the two are closely related, probably products of a recent fragmentation event. These are SOHO-856 and SOHO-857.

It seems that Tsai-Yuan Sheng has gained a measure of reknown in Taiwan for his September 24 discovery of his first SOHO comet. See this news story from the Taiwan Journal. "Tsai's discovery made a huge splash in the Taiwanese press because he is Taiwan's first discoverer of a comet using the SOHO images," the story mentions. Tsai's Kreutz find was one of the brightest comets discovered this year in SOHO images, but was only visible in a handful of images due to gaps in the data.

October 27, 2004

The past couple of days have been busy on the SOHO comet front. Yesterday morning (New York time), Hua Su reported a Kreutz comet in slightly delayed C2 images. It was spherical-shaped, and quite faint. Last night, John Sachs reported a C3 Kreutz comet. I checked his positions, and found a very faint object; its motion was entirely consistent with that of a Kreutz comet over four positions, so I confirmed it. Sure enough, it was real; as it was found near the edge of the field, it had plenty of time to develop. It sprouted a short tail and became fairly bright in C3, brilliant in C2. Just when it had faded out this evening, another C2 comet was found, this one by Bo Zhou; it was faint and teardrop-shaped.

Today, Karl Battams officially confirmed recent SOHO comets up to SOHO-854; Bo's will make it 855. Karl also called for more restraint and careful checking when posting claims; there has been a spate of multiple reports and follow-ups for the same object often when it had first been reported many hours before; also, people had been confirming their own claims, or confirming claims for the wrong person. Newcomers will no longer be allowed to confirm comets until they prove themselves, and there will be a place on the form to report close fragments/companions to known comets.

October 24, 2004

Yesterday, Xavier Leprette reported a C3 comet when it was still very faint; Hua Su reported it soon afterward. Later, both Xavier and I reported a companion fragment to it, but it didn't show up in later images, so it presumably was noise. The comet brightened, but the images from when it was getting close to the Sun are not yet available; it surely would have been visible in C2.

John Sachs has noted that Heiner Otterstedt's non-group comet, C/2004 U2 (SOHO), will pass close to Venus on November 6-7. This should change the comet's orbit--if the comet didn't completely disintegrate around perihelion.

October 25, 2004

Last night, I found a small Kreutz comet in C3, just over halfway out from the edge of the field. As it approached the Sun, it became very condensed, appearing as a moderately bright, moving speck. The comet was visible in C2 as a small, bright, spherical patch, with a trace of a very faint and narrow tail in early images; it quickly faded as it approached the Sun. This should be SOHO-852.

The images showing yesterday's passage of Xavier's comet through C2 were released today; it was similar in brightness and appearance to mine, although a little more teardrop-shaped.

October 24, 2004

Yesterday, Xavier Leprette reported a C3 comet when it was still very faint; Hua Su reported it soon afterward. Later, both Xavier and I reported a companion fragment to it, but it didn't show up in later images, so it presumably was noise. The comet brightened, but the images from when it was getting close to the Sun are not yet available; it surely would have been visible in C2.

John Sachs has noted that Heiner Otterstedt's non-group comet, C/2004 U2 (SOHO), will pass close to Venus on November 6-7. This should change the comet's orbit--if the comet didn't completely disintegrate around perihelion.

October 22, 2004

Xing Gao found a Kreutz comet in C2 images today; it is Xing's first SOHO comet. It was first reported on the images from 10:30 to 11:30 UT today; although it was in the C2 field earlier, the first images that came up did not show it due to a dark zone that obscures the edges of black-and-white images, and the color C2 images available from the NASA site. This should be the 850th comet found in SOHO images. On this date last year, the tally was at 680. If this rate of 170 comets/year were to continue, by this time next year we'd be at around 1020 comets, and SOHO-1000 could be found as early as next summer.

I have not seen any reports to indicate that Comet 2004 R2 (ASAS) survived its perihelion passage to become visible in the evening sky after it passed through the C3 field. The comet probably dissolved. Bernd Brinkmann, on the evening of October 14, tried to image it from Germany using a 50 cm reflector and an ST-8 CCD camera and could not discern it, although he could make out stars down to magnitude 14.4.

October 21, 2004

Today, Heiner Otterstedt found another C3 comet, this one presumably a Kreutz. Its path, though, was about 20 degrees to the left of most of the recent Kreutz comets. This one is probably Subgroup II, and thus related to Comet Ikeya-Seki and the Great Comet of 1882; about 20% of SOHO's Kreutz comets belong to this subgroup. Later, Rainer Kracht reported that from looking at the C3 images he thought the comet was double, that there was a second comet closely trailing the first. From the C2 images, it's unclear if indeed it's a second nucleus or a knot in the first comet's tail; Karl Battams is counting it as a separate comet. This should bring SOHO's total up to 849.

The orbit for Heiner's non-group comet of October 16 was released today; it has a perihelion distance of 9.9 million km and is of high inclination (84.25 degrees), as was obvious from its motion.

October 20, 2004

Several interesting SOHO comets have been found over the past few days. On October 16, Heiner Otterstedt reported a sporadic C3 comet (not belonging to any known comet group). It was heading almost straight downward, north to south, in the C3 field, to the left of the occulting disk that hides the Sun. At first, there was some speculation that it might survive to be visible in the night sky, but as far as I can tell, it never emerged from behind the pylon that holds the occulting disk in place. It probably was an intrinsically faint comet undergoing an outburst. This is Heiner's 3rd SOHO comet discovery; two of them have been non-group comets. On October 17, Bo Zhou reported a faint C2 Kreutz comet, Bo's second SOHO comet find; it is the first Kreutz comet visible only in C2 (and not in C3 as well) in this current season. Then on October 18, Karl Battams reported a faint Meyer comet, only visible in 5 or 6 images. This should bring the total number of SOHO comets discovered up to 847.

October 14, 2004

Yesterday morning before going to work, I checked the LASCO C3 images, and near the edge of the field I noticed a faint splotch that appeared to move towards the Sun in four consecutive frames on a path indicative of a Kreutz comet. It was invisible on the fifth frame, though on the following one there was something right in the predicted position. I reported it, not sure if it was a comet or noise; when I got into work, I was pleasantly surprised to see that Rainer Kracht had confirmed it. The comet (SOHO-844) brightened and developed nicely; it was later well seen in C2 as a bright, globular spot with a short tail that faded rapidly as it approached the Sun.

Karl Battams has internally confirmed the 50th Meyer comet; he has done the astrometry and will submit the data to Brian Marsden tomorrow. The comet is only visible in 5 images as it crossed the upper right corner of the C2 field, but it was clearly visible so I doubt that Brian will have a problem calculating a basic orbit for it.

October 12, 2004

Rainer Kracht found the 50th Meyer-group comet today in images from October 8-9; congratulations to him as well as to Maik Meyer, who discovered this comet group. This is Rainer's 133rd SOHO comet, which puts him just 10 comets behind Michael Oates for the all-time lead. (I had actually downloaded and presumably reviewed the images in which the comet appeared, but although I usually make a point of checking for comets from the new groups, I had somehow missed it--perhaps because of the peculiar image flow: two images 10 minutes apart, then nearly an hour before the next image, then more than an hour's gap until two more images came in quick succession). Early today, Hua Su discovered a C3 Kreutz comet from October 10 in more than two days worth of images that were uploaded at once. It was easily seen as a tailed comet in C2.

The two "guest comets," C/2004 R2 (ASAS) and C/2003 K4 (LINEAR) have completed their passage through LASCO C3. (R2 was briefly visible in C2, as well.) R2 faded notably as it approached the edge of the field, north of the Sun. Its tail continued to trail it as it passed northward, seemingly pointing toward the Sun (though this may have been largely a matter of perspective) until it nearly had left the field. The comet may soon be visible in the evening sky for Northern Hemisphere viewers, faded to perhaps 10th magnitude. On the other hand, K4, which had been inconspicuous throughout its passage across C3, brightened somewhat as it approached the field's edge. It will soon be a morning object for Southern-Hemisphere viewers.

October 6, 2004

Yesterday, C/2004 R2 (ASAS) entered C3 as an easily visible, teardrop-shaped comet sporting a straight tail about 1/3 degrees long. It's now passing about 2 degrees from C/2003 K4 (LINEAR), which seems a barely conspicuous smudge in comparison. Comet ASAS, in its appearance and motion, actually resembles a bright Kreutz comet (though it bears no relation to that sungrazing comet group), making a beeline for the Sun, or rather for the right side of the occulting disk; it will cross C2, the LASCO narrow-field camera that just shows the immediate vicinity of the Sun, but then will continue north of the Sun, and with any luck will emerge to become visible in the evening sky for Northern Hemisphere viewers. Maik Meyer, who runs the Catalog of Comet Discoveries Web site, estimates that ASAS currently is no brighter than 6th magnitude

Two new comets were found in LASCO C3 yesterday, bringing SOHO's total to 841. I'd woken up very early yesterday morning and had a look at LASCO; only three images were available due to a gap in the images. In them, fairly close to the Sun and fading quickly, I could see a fairly faint Kreutz comet. I looked at the reports page, to find that Hua Su had already reported it, and Xavier Leprette soon afterward. It became easily visible in C2. Later yesterday afternoon, Rainer Kracht reported a comet in C3, once again after a gap in images. It, too, became easily visible in C2, teardrop-shaped and with an obvious tail. For Rainer, who has been the most prolific SOHO comet hunter over the past couple of years and is closing in on Michael Oates's all-time record of 143 SOHO comet discoveries, it is the first SOHO comet he's found in more than 3 months.

October 2, 2004

C/2003 K4 (LINEAR) has been creeping across the C3 field of view for four days now, still faint and rather condensed, with no clear tail. In a couple of days, C/2004 R2 (ASAS) will join K4 in the C3 images. See the chart at the Sungrazer Web site for their tracks. It will probably be at the fringe of SOHO's visibility (unless it's brightened much in the past few days; it was 8th magnitude on September 27) and it's doubtful it will survive perihelion.

The late Chinese comet hunter, XingMing Zhou, who died in a motorcycle accident in August, has been immortalized with a place in the heavens. A main-belt asteroid, Minor Planet 4730, has been renamed (4730) Xingmingzhou. It is no coincidence that an asteroid was chosen whose original designation, 1980 XZ, contains XingMing Zhou's initials, nor that it was discovered at China's Purple Mountain Observatory. XingMing was the fourth most prolific SOHO comet hunter, with 63 LASCO and 1 SWAN comet discoveries; he was also the independent discoverer of night-sky comets 1990n1 (Tsuchiya-Kiuchi) and 122p/de Vico.

September 28, 2004

Hua Su found a comet in C3 today (SOHO-839); it was moderately bright, condensed, and visible after a gap in images; it was easily seen in C2 for several images as well. Yesterday, Comet 2003 K4 (LINEAR) entered the left edge of the C3 field yesterday; it will take about 10 days to pass through the field. It appears condensed, fuzzy, tailless, and fainter than I'd expected. To the right of the Sun in the C3 field, three planets are now tightly grouped: Venus, Jupiter, and Mars.

September 24, 2004

As the first new images after the SOHO spacecraft's roll maneuver were coming up two nights ago, a bright Kreutz comet was visible, heading in towards the Sun. It was reported first by Tsai Yuan-Sheng; this is Tsai's first SOHO comet discovery (SOHO-838). Unfortunately, there were large gaps in the image flow, but it was clearly one of the brightest SOHO comets that we've seen in a while.

September 20, 2004

In the last string of C3 images before SOHO was "safed" in preparation for its roll, Karl Battams found a comet in C3 (SOHO-837). Though only visible in 9 images because of the image flow problems, it was clearly visible towards the edge of the field, and presumably became moderately bright. There will be no new LASCO images until Thursday.

September 19, 2004

There have been no new SOHO comets reported in nearly two weeks, though of late the mission has been hobbled in the past few days by the antenna problems that cause long gaps in image reception for a few weeks out of every few months. They can be corrected by rolling the spacecraft, a maneuver that will take place early this week; normal reception of images is expected by Thursday.

September 9, 2004

A new comet has been discovered in ASAS (All-Sky Automated Survey) data. It was found on September 3, and has since been observed in the night sky; it was not officially confirmed until today. This 10th magnitude comet is in Puppis, at a declination of -21. Though not a sungrazer, C/2004 R2 (ASAS) has a fairly small perihelion distance; it will pass 0.11 a.u. from the Sun on October 7. An intrinsically faint comet, it may not survive perihelion. It will pass through SOHO's LASCO C3 (October 5-10) and C2 (October 8). If it does survive, it could reach about 2nd magnitude in SOHO images; it would likely fade rapidly as it emerged into the evening sky for Northern Hemisphere viewers.

September 7, 2004

This weekend brought a bit of a flurry of four Kreutz comets. On September 4, Hua Su found a comet near the edge of the C3 field, which became the brightest of the four; it later was faintly visible in C2 images. Later, John Sachs reported a fainter C3 comet preceding it. On September 7, Hua Su found another faint comet following his first find in delayed images from September 5. Karl Battams then posted positions confirming what he thought was Hua Su's comet, but they turned out to be yet another comet, following it. Though Karl's comet only appeared about midway across the C3 field, it was clearly visible later in several C2 images. This brings SOHO's grand total to 836 comets.

August 30, 2004

Some sad news: Dr. Fred Whipple died today, at the age of 97. He had worked at the Harvard College Observatory since 1931, and from 1955 to 1973 directed the Smithsonian Astrophysical Observatory. He was best known for developing the theory of comets as "dirty snowballs."

An orbit for Comet Machholz (2004 Q4) has been released and now revised. The comet should make a nice pass northward starting in December, when it passes from Eridanus into Taurus. In January, it speeds from Taurus through Perseus into Cassiopeia; on the night of January 6-7, it will lie 2.5 degrees from the Pleiades. It will pass 0.35 a.u. from Earth in early January, and reach perihelion at 1.20 a.u. from the Sun on January 24, when it could be about fourth magnitude, thus easily visible with the naked eye from reasonably dark skies--time will tell, though, how it performs.

August 27, 2004

It's probably not a near-Sun object, but today California amateur Don Machholz visually discovered an 11th magnitude comet. It is his 10th comet discovery, though his first in a decade. He found it with a 0.15-m f/8 reflector, at 30x. Gordon Garradd and Rob McNaught have made follow-up observations from Australia. The comet is in the morning sky in the constellation Eridanus, at a declination of -22, and heading south (at least for now); it is too soon to have an orbit or ephemeris.

August 26, 2004

Yesterday Xavier Leprette discovered a faint C3 Kreutz comet (SOHO-831) today; his first reported position was 11:18 UT, but it can be seen, very faintly, tracking across the C3 field of view for several hours before that (and several hours after). It appeared condensed, although a bit wispy in earlier images. Last night I found a C3 Kreutz as well (SOHO-832); I saw it distinctly with a short tail in two images, nearly halfway across the C3 field, and reported it then. It fluctuated greatly in brightness and appearance in the first few hours, showing a short tail at times, diffuse at others, and sometimes nearly starlike. Though easily visible as it crossed C3, it never became particularly bright.

August 24, 2004
Today Karl Battams confirmed two C3 Kreutz comets, found by me (August 19) and John Sachs (August 20), respectively. This brings the number of SOHO comets found to 830. Both comets became moderately bright; SOHO-829 was found near the edge of the C3 field and was visible for a day.



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