SOHO/Near-Sun Comet News and Views
2006 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.

Current News
2007 News
2005 News
2004 News

November 22, 2006

I'm sorry that it's been so long since I last updated these pages. Shortly after my previous report I had to have Windows reinstalled on my machine, which wrote over my old applications, including the Web design program I'd been using (Arachnophilia). I had been hoping to switch programs as Arachnophilia is quite primitive (even with it, I do most of the coding myself by hand) and tried a couple of new ones, but couldn't find one with which I could make good tables, and then I became too busy to experiment. For the moment, I'm back with Arachnophilia--If anyone knows of a good, freeware or inexpensive Web design program, please let me know. I will try to keep these pages updated more regularly.

With Karl's latest round of confirmations, the SOHO comet count is up to 1225. The most spectacular SOHO comet found in the past couple of months was a very bright Kreutz, one of the brightest ever seen in SOHO. I found a double Kreutz on November 20 UT, and a Meyer comet a month ago; most of the other comets found lately have been single Kreutz comets, mainly in C2. The Stereo/SECCHI mission was launched, and Karl says that eveerything is going well with it; we'll probably see the first images from it in January.

September 26, 2006

For nearly a month, up until last week, SOHO went through a keyhole period that drastically reduced SOHO's image coverage. Between August 4 and September 18, only two SOHO comets were found, a Meyer-group comet by Hua Su on September 2, and a C3 Kreutz by me on September 11. I found the C3 Kreutz after a gap in images; it was obvious, even though still near the edge of the C3 field, so it had the potential to become brilliant. Unfortunately, it was only visible in seven images after which there was a long data gap, so we'll never know how bright it got.

On September 18, Rob Matson found an amazing five realtime SOHO comets, all visible in both C2 and C3. This included one close pair, and another pair in which one comet followed the other by a few hours. (I actually reported the trailing member of the second pair in C3, thinking it was a new comet, but it turned out that Rob had already reported it in C2, thinking it was the entry of the leading member of the pair, which he had already reported in C3.) An amazing day for SOHO comets, and for Rob.

August 17, 2006

Rob Matson, co-discoverer of Comet 2006 M4 (SWAN), was the first to detect the comet in C3. The comet is still very faint (it's amazing that Rob was able to detect it), but it should brighten in the coming weeks.

August 12, 2006

Comet 2006 M4 (SWAN), discovered nearly a month ago in SOHO's SWAN images by Rob Matson and Michael Mattiazzo, should be in the C3 field by now (at the extreme lower left), but it hasn't been reported, so it is presumably still too faint. Hopefully that will change as the comet approaches perihelion; it will remain in the C3 field for more than two weeks, finally exiting to the upper right around August 28. It will pass through C2 from August 19-23, but due to SOHO being in the middle of a keyhole period, image coverage may be greatly curtailed. Karl Battams has prepared finder charts for both C3 and C2. (See his news page for August 1).

On August 9, Karl posted confirmations for six SOHO Kreutz comets. This included the first SOHO comet by Shihong Yuan of China (a nice object visible in both C3 and C2, the only C2-visible comet of the current confirmations) and the first 3(!) SOHO comets for Arkadiusz Kubczak of Poland, includiing the 100th SOHO Kreutz comet (SOHO-1185)! The two other comets in this batch were found by Hua Su, who also--since my last update--found a companion to the bright Kreutz he found on July 25--both components were visible in C2 as well as C3.

Among the asteroid namings in the Minor Planet Circulars of August 6 was one for an object of particular significance to me, a main-belt asteroid about 2km in diameter with the name 112900 Tonyhoffman. Many thanks to Rob Matson for this great honor. Rob found the minor planet in NEAT images from Mt. Palomar taken in 2002. Here is an orbital diagram. The asteroid is currently near opposition in Capricornus and is about magnitude 20. This would seem to be the 7th asteroid named for a SOHO comet discoverer; others include 4730 Xingmingzhou, 73491 Robmatson, 68946 Mikeoates, 51983 Honig, 52005 Maik, and 35461 Mazzucato.

July 25, 2006

Today, Hua Su became the fourth SOHO hunter to find 100 comets by finding a C3 Kreutz comet, less than two years after his first discovery. His latest was found well away from the sun and has the potential to become rather bright. Hua has found five C3 comets in the past two weeks; his discovery of July 23 was also visible in C2 yesterday.

July 23, 2006

Today, Hua Su found a Kreutz comet in C3. Hua also found C3 comets on July 20 and 21; neither of them were visible in C2. Hua's latest comets brings him to 99 by my count; one more and he will join Rainer Kracht, Michael Oates, and Xavier Leprette as the only people to have found 100 SOHO comets. The twin STEREO solar observatories are now scheduled for launch in late August and should be fully operational (and presumably discovering comets) a month or two after that. According to Karl Battams, though, many if not most of the near-Sun comets will continue to be found in SOHO images; although STEREO is more sensitive and has a wider field of view, its images will be posted once a day while SOHO's will still be released in real time.

July 19, 2006

Today, Karl Battams confirmed five SOHO comets that I mentioned in my last report, bringing the total to 1,174. It includes the SWAN comet, but not the C2 Kreutz comet that I found on July 14. It was only visible in 3 positions, so it becomes an X/comet.

Karl also mentioned (in the Yahoo Sohohunter group) that the launch date of NASA's STEREO mission has been pushed back to no earlier than August 20. STEREO will consist of twin solar observatories, one positioned ahead of the Earth and the other behind it, taking images at the same time to create 3D pictures of the solar corona, CMEs--and comets. Its detectors will be more sensitive than SOHO's, and the field of view wider, but the images will only be made available once a day en masse, so it's likely that SOHO will still find its share of near-Sun comets.

July 17, 2006

Rob Matson and Michael Mattiazzo have co-discovered a comet in images from SOHO's SWAN (Solar Wind Anisotropies) instrument. At just 12th magnitude, C/2006 M4 SWAN is just barely visible in SWAN images. It was confirmed by Rob McNaught and other ground-based observers, and a prediscovery image of it was found by Terry Lovejoy. According to the orbit published in an MPEC on July 15, it will reach opposition on September 28. It should brighten to about 8th magnitude in September and October when it will be well placed in the evening sky for Northern Hemisphere observers. It should be visible in LASCO C3 from about August 11 to August 28, and in C2 between August 18 and August 23. We're looking forward to a good show.

The past week has seen several Kreutz comets. Steve Farmer found a faint C3 Kreutz comet on July 11 that was nonetheless visible in C2. On July 13, Hua Su found a C3 Kreutz. On July 14, I found a faint C2 Kreutz, though I can only make it out in 3 positions, so it probably won't be confirmable unless it's visible in C3. On July 14, Wentao Xu found a moderately bright C3 Kreutz that was also well seen in C2. And on July 17, I found a faint, slightly elongated C3 Kreutz--it is my 75th SOHO comet (unless I get credit for the July 14 C2 Kreutz).

July 10, 2006

Sorry for the delay in updating; I'd been traveling quite a bit over the past couple of weeks. Several new comets, all C2 Kreutz have been found since my last update. On June 19 I found an obvious (though not bright) and fairly condensed Kreutz comet in delayed C2 images. Hua Su found one on June 22, and two on June 27, one of which was a co-discovery with Tao Chen, who reported it 6 seconds earlier. It has been two weeks since any SOHO comets have been found.

On June 27, Brian Marsden and I were presented with a popular writing award from the solar physics division of the American Astronomical Society for the article we co-wrote on SOHO comets that appeared in the August 2005 issue of Sky and Telescope. It is one of two awards that are presented each year by the solar physics division for articles that help popularize some aspect of solar or heliospheric study. Brian and his wife drove up from Massachusetts, and I drove up from New York, to accept the awards at the solar physics division's annual meeting in Durham, New Hampshire.

June 10, 2006

Since LASCO came out of safe mode three days ago after SOHO was flipped, three new SOHO comets have been found, all quite faint C2 Kreutz comets. Hua Su found an especially faint one on June 8. Guoyou Sun found another, also in images of June 8, then I found another one today in delayed images. I would like to dedicate this discovery to my mother, who died unexpectedly three weeks ago, a day after suffering a massive stroke. Thanks to me, she probably observed more comets than many astronomers, and she was always impressed by the things I was able to find and intrigued by what I'd tell her about the latest advances in astronomy. She was a great lover of nature.

June 2, 2006

I'm sorry, I missed one congratulation in my previous post: to John Sachs, for passing the 50-comet mark. Gouyou Sun found his 4th SOHO comet in C2 on June 2. Karl confirmed 10 more comets, including many of those mentioned below and also a non-group from December 1999.

May 25, 2006

Several congratulations are in order: to Gouyou Sun, for finding his first three SOHO comets(!), to Luciano Cane, for finding his first, and to Rob Matson, for passing the 50-comet milestone. Karl Battams confirmed 10 more comets on May 23, including two by Rob Matson (two more since then has brought his total to 51), four by Hua Su (including a faint C3 non-group comet visible above Venus in nine images from May 22), one by Wentao Xu, one by Bo Zhou, Luciano Cane's find and the first of Gouyou Sun's three comets. One of Hua Su's and one of Rob Matson's Kreutz comets were visible in C3 as well as C2; the rest were C2 only. Since then, in addition to the other comet I mention above, Tao Chen found a C2 Kreutz.

Funding for the SOHO mission has been extended until 2009. By that time it should be one of a fleet of solar observatories, including Japan's Solar-B, ESA's Proba-2, and NASA's STEREO and Solar Dynamics Orbiter.

May 13, 2006

Yesterday, Karl Battams confirmed eight comets, all found between May 8 and 11--the spring "comet storm" season for C2 Kreutz discoveries is in full swing. Karl found a C3 Kreutz comet in delayed images on May 8 that got bright and was well seen in C2 as well. Also on that day, Hua Su found a Meyer comet tracking almost vertically to the left of the Sun in C2. Rob Matson and John Sachs also jointly found a C2 Kreutz that day; they reported it 16 seconds apart. Another joint C2 Kreutz discovery was made on May 10; Hua Su and Tao Chen reported the comet just two seconds apart! That same day, I reported a double comet, two small, round, relatively faint Kreutz comets, the fainter one closely trailing its slightly brighter companion. On May 11, I found another C2 Kreutz, small, round, and diffuse, with just a hint of a tail. Half a day later, John Sachs found a similar C2 object.

This recent active period for SOHO discoveries was preceded by a more than a month of relative quiet. Since my last report, Hungarian amateur Adam Ambrus found his first SOHO comet, a Kreutz that was well seen in C3 and later in C2. On April 28, Hua Su and John Sachs reported a C3 Kreutz 20 seconds apart; it was also seen in C2. The other comets found during that period were all C2-only Kreutz objects, four by Hua Su, one by Karl Battams, and one by me.

April 15, 2006

Yesterday, John Sachs reported a C2 Kreutz comet; Hua Su also reported it less than a minute later. It was moderately bright and had a short tail. Early on the morning of April 11, I found a C2 Kreutz comet; it was faint, round, small, and diffuse. The LASCO site is down for the weekend; I don't see any new images on the Nascom site, either.

March 31, 2006

Two days ago, Karl Battams confirmed five comets; my recent Marsden and Meyer finds, plus an archive Kreutz from June 1998 found by Rainer Kracht, a faint C2 Kreutz found by Rob Matson on March 28, and a bright Kreutz found by Hua Su on the morning of March 29 when still very near the edge of the C3 field. (though bright, it remained largely stellar in appearance in C3 and showed a faint, narrow tail in C2.)

New MPECS have been published, for 6 Kreutz plus 1 Meyer from January, plus the two recent Marsden comets. The orbit of C/2006 A5 (SOHO), or SOHO-1087, the very bright Kreutz comet that was visible in SOHO in early January (see its image at the top of this page) is of particular interest as its published perihelion distance (0.0043 AU) is smaller than the Sun's radius (0.00465 AU), meaning that if the orbital elements are correct, the comet was on a collision course with the sun, though it seemingly vaporized shortly before impact. The comet, still bright as it entered the C2 field and trailing a narrow, straight tail that eventually stretched across the entire field, faded rapidly as at approached the Sun at more than 700,000 km/hr,until finally it was all tail, with no discernable head. The last data point used to calculate the orbit was only about 80 minutes before perihelion. Only about 6 SOHO comets have had published orbits that indicate they might be sunstrikers; however, Brian Marsden has emphasized that there is a lot of uncertainty in the orbits due to their short observational arcs and the relatively low resolutions of the SOHO coronagraphs (11 arc-seconds in C2 and nearly an arc-minute in C3), and it's likely that some comets with published sunstriker orbits weren't sunstrikers, and vice-versa. SOHO-1087, however, was observed in about 60 positions, so its orbit is perhaps more accurate than many of the others. Karl Battams also reported that SOHO-1087's peak recorded brightness was between magnitudes 0 and -1 when it was around 11.5 solar radii from the Sun. It became even brighter, and peaked at around 10 solar radii from the Sun, but its brightness couldn't be measured due to a software bug; Karl thinks it peaked at around magnitude -1.5. There may have been five or six SOHO Kreutz comets that reached a similar or greater brightness.

March 26, 2006

I found an apparent Marsden comet in the early UT hours today (last night, New York time). It was visible in 6 images, the first 4 separated from the final 2 by an hour's gap. It will be interesting to see if this comet and the one found by Rob Matson can be shown to be returns of Marsden comets seen in February 2000, but there may not be enough positions.

March 22, 2006

Tonight I reported what appears to be a Meyer comet, cutting across the upper left corner of the C2 field. It's only visible in four images so far, after which there's a gap-- hopefully the remaining images will come up later.

Today, Karl Battams announced eight new confirmations, bringing the SOHO count up to 1116. These included the recent comets found by me (on March 15, Michele Mazzucato, Rob Matson, and Hua Su, plus four more archival discoveries from 1997-98 by Rainer Kracht: two Kreutz (including a C2 Kreutz that was relatively bright), a Meyer, and a small, stellar-looking C2 non-group comet.

March 21, 2006

This morning, Michele T. Mazzucato reported a faint C3 Kreutz comet, a small splotch just out from the left edge of the pylon. Congratulations are in order, as this is Michele's first SOHO comet.

March 16, 2006

Yesterday, Rob Matson found a very faint Marsden comet in C3, climbing almost vertically to the left of the Sun, in images from the early hours UT of March 15. (Because of image gaps, the only available C3 images showing the comet are between 0218 and 0842 UT on March 15.) It's possible that it is also seen exiting the top of the C2 field in images of 0048 and 0100 UT; hopefully the earlier images will become available at some point.

March 15, 2006

At long last, I have updated all the totals of comets that Karl has confirmed. The official count is up to SOHO-1106, with two yet to be confirmed; I found one of them tonight, the first C2-only Kreutz, it would seem, of the year. One of Rainer's archive comets was a Meyer, as was a realtime discovery by Hua Su.

January 10, 2006

Yesterday, I found a faint and condensed (stellar-looking) C3 comet, visible intermittantly in about 8 images before I reported it. It came on an unusually high arc from the left; I suspect it may have been Subgroup II. It was visible in more than 20 C3 images, but apparently not in C2. This is presumably SOHO-1088.

SOHO-1087 is being featured as the Pick of the Week on the SOHO Web site.

January 5, 2006

Yesterday's C3 comet got very bright as it neared the sun, and its tail grew to be over a degree in length. It was well seen in C2, too, with a straight and narrow tail that ultimately extended from the edge of the C2 field to the occulting disk. This will be SOHO-1087.

January 4, 2006

Last night, I found a C3 Kreutz comet after an image gap, in images from early January 4, UT. Though near the edge of the field, it was obvious, small and condensed. It quickly brightened as it climbed towards the Sun, to the left of the Sagittarius Milk Dipper, which is visible in C3. Today it has gotten very bright, with a tail of about 1/2 degree in length.

January 3, 2006

Yesterday, Rob Matson found the first SOHO comet of 2006, a faint C3 Kreutz that was also visible in a few C2 images. Karl Battams confirmed it, along with three archival Kracht comets from December 5-6, 1996 (including the two aforementioned bright ones) and three archival C2 Marsden comets from January 29, 1997, all found by Rainer Kracht.

For 2005, Hua Su led all SOHO hunters with an extraordinary 55 realtime comets ( + 1 archival find). The year's 7 new SOHO comet discoverers were all Chinese, Yuan-Tseng Tsai (who discovered a very bright Kreutz at the beginning of 2005) from Taiwan and the others from mainland China: Chong Liang, Jinao Zhang, Tao Chen, Quanzhi Ye, Wentao Xu, and JianGao Ruan. The latter two discovered their first comets within 5 minutes of each other, the two components of a "twin" pair of C3 comets. In addition, two SWAN comets were discovered, C/2005 P3 (SWAN), found by Hirohisa Sato, Masayuki Suzuki, Michael Mattiazzo, Michael Jäger, and Vladimir Bezugly and C/2005 T4 (SWAN), found by Michael Mattiazzo and Rob Matson. Both SWAN comets were briefly visible in the night sky.

E-mail to tonyhoffman [at] earthlink [dot] net