SOHO/Near-Sun Comet News and Views
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.
December 31, 2005
Since my last report, ten more SOHO comets have been
discovered. The official toll is up to 1079, not including two bright
Kracht comets, visible in both C2 and C3, that Rainer Kracht found in
archival images from December 1996. (These may be the precursers of
several Kracht comets seen in images of September 2002.) Rainer also
found two realtime comets, a Kreutz and an obvious Meyer comet in
images from December 26. Also on December 26, Steve Farmer, Jr. found a
C3 Kreutz comet that got quite bright and was also visible in C2. Karl
Battams found two Kreutz comets in C2 images of December 22. Quanzhi Ye
found two Kreutz comets, on visible in C3 and C2, the other a faint C2
comet. And Sebastian Hönig found a C2 Kreutz comet.
December 17, 2005
Last night, Steve Farmer, Jr. discovered a non-group C2 comet
in images from soon after LASCO came back online after a SOHO roll
maneuver, in images of early December 17, UT. The comet tracked from
left to right like a star, at a glance it might have been mistaken for
one, but it moved faster than the stars and was slightly diffuse. The
comet was obvious in C2, fairly steady in brightness until it reached
the edge of the C2 field, and also barely visible in C3.
December 14, 2005
I just updated the totals on the Discoverers' Totals page
(see the link at top of this page); I'm sorry I haven't been able to
update these pages regularly. Karl Battams confirmed eight comets
today, to bring the SOHO total to 1070. Among the more interesting
comets since my last update were an obvious Kracht comet found by Bo
Zhou in delayed realtime images on November 23, seen exiting the C2
field to the right of the Sun, and a bright Marsden comet found by Hua
Su, visible in both C2 and C3, on November 29.
November 22, 2005
Today, Karl Battams confirmed 10 comets, bringing the SOHO
count up to 1056. These included a very bright Marsden comet, visible
in both C2 and C3. This comet, C/2005 W1, may be the return of C/2000
C4. Hua Su also found two faint Meyer comets and a bright Kreutz, plus
three more since my last update that Karl confirmed on November 9;
these included a C2 non-group that crossed the upper left corner of the
field of view. Toni Scarmato also found a Kreutz, visible in both C2
and C3. Quanzhi Ye found his third SOHO comet, a faint C2 Kreutz; I
also found a quite faint C2. But perhaps the most memorable objects
found were a pair of "twin" Kreutz comets found in C3 that traveled
together side by side and were also visible in C3. They were found
about 7 minutes apart by 2 Chinese hunters, Wentao Xu and Jiangao Ruan,
and it was the first SOHO comet discovery for each of them!
November 4, 2005
Today, Toni Scarmato found a C3 Kreutz comet; it remained fairly faint
in C3 but was brighter in C2, and showed a short tail. This should be
SOHO comet no. 1042.
November 3, 2005
Tonight, Hua Su found a C2 Kreutz comet. It was faint and
quite condensed, stellar in appearance. Hua found C2 Kreutz comets
yesterday and on October 30 as well. Yesterday's was faint, with a
trace of a tail; the October 30 object was faint, round, and slightly
Several other SOHO comets were found since my last update. Rob Matson
and Michael Mattiazzo found C/2005 C4 (SWAN) in images from SOHO's SWAN
instrument around October 17; it was later confirmed by noted observers
Eric Christensen and Rob McNaught in the night sky. See Rob Matson's
discovery story by clicking on the Recent News link on the SOHO Sungrazers site.
C/2005 C4 (SWAN) is an intrinsically faint comet that
reached perihelion on October 9 at 0.65 A.U. from the Sun. It has a period of around 27 years.
The other recent SOHO comets include a C2 Kreutz found by Hua Su on
October 19, a C3 Kreutz found by Toni Scarmato on October 21, a Kreutz
comet visible in both C2 and C3, found by Bo Zhou on October 23, and a
C2 Kreutz found by Quanzhi Ye on October 24; it is Quanzhi's second
October 18, 2005
Today Hua Su found two C3 Kreutz comets, a faint one early
this morning and a brighter one later today. This should bring the SOHO
count to 1033.
October 16, 2005
I am sorry that I haven't been able to keep these pages up to date as
regularly as in the past. The SOHO comet total has risen to 1031,
though Karl Battams has not yet confirmed the most recent two. These
were a C2 Kreutz found by Hua Su (the first Kreutz comet discovered in
C2 in 3 months) on October 14, and a C3 Kreutz that I found later that
evening. It appeared suddenly about 1/4 of the way in from the edge of
the C3 field of view, brightened quickly, and followed a Kreutz
Subgroup II track clockwise of most of the Kreutz comets found this
time of year. It developed a narrow tail that persisted as the comet
passed behind the C3 occulting disk, but the C2 disk as well.
The other comets found since my last report include two Kreutz comets
discovered by Bo Zhou, both found in C3 and also visible later in C2.
The other three were found by Hua Su Two were C3 Kreutz comets also
visible in C2; the third was a C2 Meyer comet. The Meyer comet was Hua
Su's fiftieth comet, an incredible achievement as it came just 14
months after Hua's first find.
September 28, 2005
Yesterday, Hua Su discovered a C3 comet, visible from the edge of the
field. It has become quite bright, and it's still out near the edge of
the field. It should be fun to watch for the next couple of days. This
September 27, 2005
It's been a busy week, with 7 new comet discoveries, all Kreutz comets
found in C3 that were later visible in C2. Five of them, and nine out
of the past 11 comets, were found by Hua Su, bringing Hua's total to
46. Tao Chen also found a comet; this is Tao's second. And
congratulations to Quanzhi Ye for finding his first SOHO comet.
September 19, 2005
Today Karl Battams confirmed four comets, his first confirmations in
several weeks, bringing SOHO's total to 1016. All four were Kreutz
comets found by Hua Su, and they include the two I mentioned in my
report from September 7, plus another found on September 15 and another
found yesterday. All were visible in C3; the two most recent were also
visible in C2. The one found yesterday was particularly interesting. It
was moderately bright, with a short tail, and it came from a point
about 25 degrees below (clockwise from) where most Kreutz comets
approach the Sun; it no doubt was a Kreutz Subgroup II.
In a paper accepted for publication in
Astronomy & Astrophysics
Sebastian Hönig links two SOHO comets, C/1999 R1 and C/2003 R5, as
apparently being a single comet with an orbital period of 4 years.
These comets, along with C/2002 R5 (SOHO), had been presumptive members
of a possible new comet group ("Kracht2"). The paper, for which a preprint is available,
shows that the latter comet may have separated from the main object in
the late 1800s. The return of C/2002 R5 is predicted for next summer,
assuming an orbital period similar to that of the main object.
August 30, 2005
On an IAU circular from August 25 or 26 came the announcement of the
discovery of C/2005 P3 (SWAN), a comet first detected in SOHO SWAN
images by Hirohisa Sato, Masayuki Suzuki, Michael Mattiazzo, Michael
Jäger, and Vladimir Bezugly. The first visual confirmation of this
magnitude 9.5 comet was by Alan Hale on August 25. This comet can be
seen on SWAN images going back to August 4; it quickly climbs out of
the solar glare. It is in Ursa Major, and is expected to fade, even as
it becomes well placed for observing, becoming circumpolar. By late
September, it will be in the bowl of the Big Dipper, and perhaps 12th
magnitude. It is uncertain what "SOHO number" this comet will be given,
but after several recent finds, it looks like SOHO's total has climbed
Yesterday, Hua Su reported a C3 Kreutz comet, still far from the Sun.
It turned out that Steve Farmer, Jr. had submitted an earlier e-mail
claim, so he will get credit for it. Bo Zhou found another C3 comet
today, which trailed Steve's comet; both became moderately bright but
were apparently not visible in C2.
Last night (or early this morning, UT), I reported a fairly faint
non-Kreutz comet entering C2 as a Marsden comet. On close examination,
though, the comet was moving much faster than the average Marsden comet
(~100 pixels/hour, compared to about 66 pixels/hour that Rainer Kracht
cites for a Marden comet entering C2 in August). Also, its trajectory
was a little below the nominal track for a Marsden comet at this date.
I soon realized that both of these characteristics--as well as a rapid
fading-- were shared by a C2 comet I reported on August 20, 2003;
originally thought to be a Marsden comet, its orbital elements make its
relationship with the group uncertain; its perihelion distance is
considerably less than other Marsdens (.032 AU, compared to a mean of
.048 for the group), and its other orbital elements (except
inclination) are divergent enough from any Marsdens to make it an
anomaly. I wonder, though, if my new comet might not be closely related
to it. I look forward to its orbit; unfortunately, it's only visible in
7 or 8 positions.
August 25, 2005
Yesterday, Steve Farmer, Jr. found a C3 Kreutz comet when it was still
fairly far from the Sun; it brightened, though it remained fairly
condensed in appearance. This morning, Hua Su found a Meyer comet, this
one almost hugging the very edge of the C2 field in the upper right
corner. It was visible in 7 positions altogether. This should bring the
SOHO comet total to 1008.
August 23, 2005
Early this morning (just after midnight, local time), I reported a
Meyer comet in C2. Although it was moderately bright (perhaps magnitude
6.5, Karl says), it was difficult to find and to confirm, as C2 was
covered with spots of noise ("snow") from a particle storm. It was
visible, though, from the image where it entered the field (it cut
upwards across the upper right corner) to to the one in which it left,
only covered in a single (of 10) image by a cosmic ray hit. This should
be Meyer comet no. 60.
August 21, 2005
Early on August 19, Hua Su found a fairly faint non-group comet in C2.
I reported it 30 seconds later, and Maik Meyer about 2 minutes after
me. The comet emerged from the lower right corner of C2 and headed
towards the bottom of the Sun, moving quickly and fading.
August 17, 2005
Today, at last, came the official announcement of the discovery of
SOHO-1000; it was the second and fainter C3 Kreutz comet reported by
Toni Scarmato on August 5. Congratulations to Toni on finding the two
comets in quick succession, with so many other people looking. Here's
the NASA press release.
put up a page on the Sungrazer site about SOHO-1000.
SOHO Hot Shot
contains an animation of SOHO-999 and SOHO-1000 approaching the Sun,
and also congratulations from the SOHO team to all the hunters who have
participated in finding its horde of comets. The SOHO operations team,
the designers of the spacecraft and especially the LASCO coronagraphs,
the professionals who have processed the claims and done the
astrometry, and calculated the orbits for these comets, are equally
deserving of praise. Finding comets was an afterthought in SOHO's
missioon to study the Sun, which was launched nearly 10 years ago, and
no one imagined the enormous number of tiny comets, most of them
fragments of some of the brightest comets known, while others represent
hitherto unknown groups of comets, which before SOHO were forever
hidden in the solar glare. The spacecraft has survived far beyond its
original two-year operational life, weathering several crises that
could have destroyed it. The count is now up to 1004, thanks to a C3
Kreutz comet that Steve Farmer, Jr. found tonight, his second SOHO
comet. Let's hope that SOHO will continue to both do its amazing work
in studying the Sun and facilitate the finding of sungrazing comets far
into the future.
August 15, 2005
Hua Su has found two more C3 Kreutz comets, a relatively faint one
yesterday and a slightly brighter one on August 12. This will bring the
SOHO comet count to at least 1003. Still no official word on SOHO-1000;
I expect a press release, and perhaps an MPEC, will come before Karl
posts any more confirmations. I know who found SOHO-1000 for sure now,
but I'll leave it to the official announcement to make it public.
August 10, 2005
Tonight I found a Kreutz comet, about halfway across the C3 field; it
is small and round and faint. We'll see how it develops. This should be
at least SOHO-1001.
Earlier today, Karl Battams confirmed SOHO comets 991-995, with "more to come sometime soon."
Toni Scarmato's brighter comet of August 5 was visible in one C2 image,
but must have faded out immediately thereafter, which is common at this
time of year for C2 Kreutz comets.
August 5, 2005
Today, Toni Scarmato found two C3 Kreutz comets in delayed realtime
images. He reported them about five minutes apart, first a brighter one
and then a fainter one preceding it. This should bring the SOHO comet
count to at least 1000! Due to several unretracted claims of faint C3
Kreutz comets by veteran SOHO hunters in first few days of August, the
identity of SOHO-1000 (and of its discoverer) is still uncertain, but
it was most likely one of Toni's two finds today, probably the second.
Soon enough, though, Karl Battams will let us know, and there will
undoubtedly be a press release forthcoming as well.
It was just a year ago today that the esteemed and masterful SOHO
hunter XingMing Zhou died of injuries suffered in a motorcycle
accident, and he has been in the thoughts of many of us. Toni dedicated
his discoveries to XingMing, and this morning, a number of the Chinese
hunters posted a tribute to XingMing on the Yahoo Sohohunter mailing list
. "Although he has gone, he will live in our heart forever," they
concluded. I am sure that XingMing's example helped inspire the
tremendous success of so many Chinese SOHO hunters over the past year.
July 26, 2005
The SOHO comet count has jumped to at least 998, with two comets I
found overnight. (I say at least 998 because there is one outstanding
claim for a faint Kreutz with reasonable positions, but I can't tell if
there's anything there.) Just after midnight, I found a C3 Kreutz,
round and fuzzy, nearly halfway from the edge of the field. It was
readily visible after a gap due to a defective image. Shortly
thereafter, I reported a faint Meyer comet threading its way among
spots of noise in the upper right corner of C2. It brightened as it
approached the edge of the field. This leaves us no more than two
comets shy of SOHO-1000.
In an impressive piece of archival work of the sort he has become
reknowned for, Rainer Kracht has found three more SOLWIND comets, two
of them Kreutz (which have been announced on IAUC 8573) and one, a
non-group, which is still pending. (SMM images are being checked for it
as well.) All are about 2nd or 3rd magnitude. Rainer has created a special section of his Web site
for SOLWIND discoveries.
July 23, 2005
Tonight I found a faint Kreutz comet about halfway across the C3 field.
It was reported by John Sachs just over a minute after me. In the 5
hours since discovery, it has remained a small, faint pointas it
advances towards the Sun. This should be SOHO-996. Karl Battams hasn't
confirmed any comets since SOHO-990, and if true to his earlier world,
won't until the 1000th SOHO comet is found. It is possible that there
are other SOHO comets among the outstanding claims, but unlikely as
none have been confirmed by other hunters nor look particularly
suspicious. So my count is unofficial, and subject to possible revision
when Karl Battams finally processes the claims.
After a nice, bright trek across C3, Rob's comet was seen in C2 earlier
today in about 9 images. It was bright when it entered C2, but it faded
quickly, showing a long, faint (nearly half a degree) tail.
July 21, 2005
Tonight, Rob Matson found what is presumably SOHO's 995th comet, a
faint C3 Kreutz that has brightened steadily and has the potential to
become relatively bright, as it was still near the edge of the C3 field
when discovered. Only 5 more comets to SOHO-1000!
July 14, 2005
Three more Kreutz comets were found in C3 over the past few days,
bringing SOHO's total to 994. On July 12, Bo Zhou found a fainter comet
trailing Rob's by a few hours; it got obscured by a coronal mass
ejection and apparently was never visible in C2. Just after midnight on
July 13, Rob Matson reported another C3 Kreutz comet about halfway
across the field; this one brightened nicely and was later visible in
C2. Later on the 13th, Bo Zhou reported another, this one preceding
Rob's by a few hours. It was considerably fainter, though, and was
never reported in C2. There were numerous duplicate reports of several
of these comets; also, it seems that a lot of newcomers are signing up
and have made their first reports. We're just 6 comets away from
Rainer Kracht has discovered a Kreutz comet in SOLWIND images from
November 20, 1981, it was reported on IAUC 8566. The comet was perhaps
magnitude 2 or 3, and showed a small tail. SOLWIND was a precursor to
SOHO, an orbiting observatory designed to study the Sun and the solar
wind. Using a coronagraph, similar to SOHO's yet less sensitive, it
detected seven comets between 1979 and 1984; the others were discovered
by project scientists. Rainer did his own astrometry, hampered by the
absence of visible stars in the field of view. The comet has been
designated C/1981 W1 (SOLWIND).
July 11, 2005
Today Rob Matson found the 991st SOHO comet, about halfway across the
C3 field en route to the Sun, a small point that is steadily
SOHO Hot Shot
is called "Family Ties Among a Thousand Comets" and discusses the
periodicity of Marsden comets, the relationship between the Marsden and
Kracht groups and Comet 96P/Machholz, and the Kreutz subgroups.
July 6, 2005
Today, Tao Chen found a faint C2 Kreutz comet, visible in just 5 or 6
images. This is Tao's first SOHO comet, and should be SOHO's 990th.
Karl Battams confirmed comets 985-990 today, from Sebastian
Hönig's comet of June 25 to Tao Chen's comet of today. We're just
10 comets away from SOHO-1000 now. Today, NASA issued a press release
announcing the approach to SOHO-1000 and saying that it would be found
by the end of the summer, though nowhere in the release does it mention
how many comets have been find. There is a table with the dates of
discovery of milestone comets (SOHO-100, 200, 300, etc.); the last
milestone listed, strangely enough, is 897.
June 29, 2005
Today, Kazimieras Cernis reported a C2 Kreutz comet; it was very faint and diffuse. This should be SOHO-989.
June 28, 2005
Yesterday, Rob Matson found two Kreutz comets, a faint C2 comet and a
very faint one in C3, which later was obvious in C2 as a round object
with a short tail. This should boost the SOHO count to 988.
June 26, 2005
, who yesterday became just the third person to reach 100 SOHO comet
discoveries, when he found a fairly faint C3 Kreutz comet approaching
the Sun from the lower right. It was well seen in C2 as well, round and
with a hint of a tail. On June 24, Sebastian Hönig found a small,
faint C2 comet. These should bring the SOHO count to 986. The window is
closing, though, on the C2 "comet storm" season; virtually no C2-only
Kreutz comets are found from July through September. This may slow down
the rush to SOHO-1000.
June 20, 2005
On Friday, Karl Battams confirmed both his comet and Xavier's, bringing
the SOHO count to 981. Three more comets have been found since then.
Yesterday, Hua Su found a non-group comet, cutting across the lower
right corner of the C2 field. It was obvious, and elongated in the
direction of motion. Tonight I reported a C2 Kreutz comet, which Hua Su
reported 24 seconds later. It was clearly visible, round and a little
diffuse, with a bit of a tail. Then Jinao Zhang reported a comet in
delayed C2 images; it was small, condensed, and moderately bright. It
it Jinao's first SOHO comet.
June 17, 2005
An article called "The Booming Science of Sungrazing Comets",
co-written by me and Brian Marsden, is the cover story in the August
issue of Sky & Telescope.
I just got my advance copies today, and one friend has already
received a subscriber copy. I'm very pleased at the way it turned out.
June 16, 2005
Karl Battams managed to find one more SOHO comet before LASCO's doors
closed. It was a moderately bright, small and round C2 comet, visible
after a gap in images. At first he thought it was Xavier's comet
entering C2, but that turned out not to be the case. Karl's comet was
also visible in C3; this should be SOHO-981.
June 15, 2005
Even as we gear up for the "SOHO-1000 watch", it's now time for the
Xavier Leprette watch. Xavier found his 99th comet today (and SOHO's
980th), an obvious C3 comet with a short tail that became visible after
a gap in images about halfway across the field of view. Hopefully
Xavier will soon become the third SOHO hunter to reach 100.
At around 15:30 UT June 16, LASCO will close its doors in preparation
for the SOHO spacecraft being rolled. It will reopen Saturday, June 18,
at about 18:00 UT.
June 13, 2005
Three more SOHO Kreutz comets were found in delayed images yesterday.
Karl Battams confirmed them today, bringing the count up to 979. Hua Su
found what was probably a Subgroup II Kreutz, coming from the lower
right corner of the C2 field. It was obvious and diffuse and
teardrop-shaped. Then I found a comet that was moderately bright,
round, with a trace of a tail, coming from a point about 15 degrees
clockwise of Hua Su's. Mine was visible in C3 as well as C2. Later, I
found a very faint and small C2 comet. Although it was visible in more
than 20 positions, none of the regular SOHO hunters confirmed it before
June 11, 2005
Two more SOHO Kreutz comets were found on June, a very faint C2 comet
found by Kazimieras Cernis and a faint C3 comet found by Bo Zhou that
later appeared as a small, bright spot in C2. Karl Battams confirmed
both comets, briging the SOHO total to 976. This was comet number 20
for both Kazimieras and Bo.
An article that I wrote, titled "Discover a Comet Online", has been published in
, a special publication of
(for which I am employed as a staff editor). The article gives a brief
overview of SOHO and sungrazing comets, as well as pointers for
newcomers. It is accompanied by an article on hunting for near-Earth
asteroids in Spacewatch images for the FMO Project. As far as I know,
the magazine is only available on newsstands, and only in the United
SOHO has gone into a
; image coverage will be reduced for the next couple
of weeks, and there will be gaps in images. The spacecraft will be flipped in about a week.
June 7, 2005
Karl Battams confirmed four comets today, the three mentioned in the
previous report plus a fragment of my C3 comet, which Bo Zhou reported;
it was visible in both C2 and (faintly) in C3. The four comets bring
SOHO's total to 974; two of them let me reach and pass the 50-comet
milestone. Karl gave Sebastian Hönig and me joint credit for the
comet that Sebastian found 5 seconds before me; that was my 50th SOHO
comet, and Sebastian's 40th. My 51st was the C3 comet of June 5, which
brightened very nicely as it approached the Sun; it was visible right
up to the occulting disk, and put on a fine show in C2, with Bo Zhou's
fragment trailing it to the lower left.
June 5, 2005
It was a busy day for SOHO comets. A fairly faint, round C2 Kreutz
comet was visible as new images came in after a gap; Sebastian
Hönig reported it first, then I reported it 5 seconds later.
Xavier Leprette and Rainer Kracht also reported it within about 2
minutes. Later, I found a Kreutz comet climbing slowly towards the Sun,
about halfway across the C3 field of view. Then Hua Su reported a C2
Kreutz comet after a gap in images, in images of June 6 UT.
In the past four days, four new (night-sky, not SOHO) comets discovered by Rob McNaught of the
Siding Spring Survey
have received official
designation. This brings Robs's total to 20, placing him 5th on the all-time list of credited comet discoverers.
June 2, 2005
Two more SOHO comets were recently found; this should bring the SOHO
total to 970. On May 31, Karl Battams found a C2 Kreutz comet in
delayed images from the previous day. He reported it before the images
were released to the public; there was still a problem with the Goddard
Space Flight Center image flow. (Just don't do that with SOHO-1000,
Karl--unless you want a riot on your hands.) Yesterday, Hua Su found a
C2 realtime Kreutz comet, in images with a lot of noise; with the
hour's gap between images that persists, it was harder to confirm
(though still clearly visible). Karl's was somewhat brighter. These
should be Karl's 10th SOHO comet, and Hua Su's 30th SOHO comet. (Hua
Su's have all been found in less than 10 months--very impressive.)
May 29, 2005
Yesterday morning, Rainer Kracht found a Meyer comet in C2 images that
had been posted the night before. Due to a peculiar image cadence, only
one new image ws posted each hour, so it took the comet only about 7
images to cross from above the Sun to the edge of the field. There was
a lot of noise in the images, and that coupled with the comet's fast
motion made it difficult to detect; I had scanned the same images
looking for Meyer comets and had missed it--but it was no problem for
Rainer, the reigning comet king.
May 26, 2005
Today Karl Battams confirmed three SOHO comets, bringing the total to
967. One is a small, faint fragment to the left of Hua Su's C2 Kreutz
of May 20; the other two are C3 archive comets found by Rainer Kracht;
one is from August 16, 2001, the other from September 28-29, 2001.
Today, two MPECS covering a total of nine SOHO comets were released. The circulars,
cover a Kreutz comet from September 2000 and eight comets from April 2005,
six Kreutz, one Meyer, and one non-group.
May 20, 2005
It was a busy week for SOHO comet hunting; with eight new comets
confirmed by Karl Battams today. All were C2-only comets, seven Kreutz
and one Meyer. John Sachs found a very faint, tailed Kreutz in images
of May 14; it appeared as a long, thin streak slightly brighter than
the background. Bo Zhou found two Kreutz comets on May 15, one very
faint one in delayed images from the previous day, and a obvious
(though not bright) one in May 15 images. That evening, I found a small
and very faint Kreutz entering C2; I could only make it out in 4 images
On May 17, Rainer Kracht found a faint Meyer comet visible in about a
dozen images from the previous day. On May 18, Hua Su reported a faint
Kreutz with a trace of a tail. Last night, I found a very faint Kreutz
with a short tail; there seemed to be a trailing fragment or two
condensations, but that was visible only in the first three images.
Today, Hua Su found yet another faint Kreutz; there may be a fragment
accompanying it, but that has yet to be confirmed.
The spate of new comets brings the SOHO count to 964, which spells the closing of the
SOHO 1000th Comet Contest
. I chose a date around August 12, but it is looking increasingly like
the date will be on the early side; I wouldn’t be surprised if it
is in mid-to-late July.
May 15, 2005
On May 10, Bo Zhou discovered two Kreutz comets in C3; one was very
stellar in appearance and the other had a bit more of a tail. They both
showed up nicely in C2. On May 12, Hua Su found a faint, globular C2
Kreutz comet. Those 3 comets have been confirmed by Karl Battams,
bringing SOHO's total to 956. Early on May 14 UT, John Sachs found a
very faint and diffuse, tailed Kreutz comet in C2 that appeared as a
streak; hopefully Karl will be able to get enough good positions for it
to make it official.
May 8, 2005
Three new Kreutz comets were found this week. On May 2, Chong Liang
reported a diffuse C2 comet with a bit of a tail. On May 5, Maik Meyer
found a very faint and diffuse comet in C2. Tonight, I found an
obvious, teardrop-shaped Kreutz comet as it entered C2. It was bright
enough to be visible in the first few b/w images as well (unusual for
C2 b/w these days because of darkening at the edges of these images);
it also proved faintly visible in C3 as well.
Asteroid 2005 HC4, discovered by the LONEOS project on April 30, has a
perihelion of only 0.0574 AU, the smallest perihelion distance of any
known minor planet. Its orbit is highly eccentric (e = .971).
April 30, 2005
Yesterday, Karl Battams confirmed Rainer's non-group and Bo's Meyer
comets, bringing the SOHO tally to 950. Now begins the push to
SOHO-1000. After SOHO-960 is confirmed, the SOHO 1000th Comet Contest
will be closed to new entries. After SOHO-985, Karl will stop
confirming archive claims until after SOHO-1000 is discovered, so as to
prevent someone from holding an archive claim in reserve, only to post
it after SOHO-999.
April 28, 2005
Tonight, Bo Zhou reported a C2 Meyer comet; it was moderately bright and elongated in the direction of motion.
The Marsden comet that Brian Marsden suspected might return at around
this time hasn't been sighted yet, and may well be too faint even if
it's survived. Or maybe it will show up tomorrow...
April 26, 2005
Three new comets were confirmed today, bringing the SOHO tally to 948.
On April 24, I reported a C2 comet; it was moderately bright, with a
short tail. There was speculation that it might be the same as an
object reported earlier in C3 by Bo Zhou, but it turned out not to be, as Karl Battams demonstrated.
Bo did find a C2 comet today, a small, teardrop-shaped Kreutz. Rainer
Kracht found a C2 Kreutz yesterday; it was fairly faint, with a trace
of a tail, and came from nearly the bottom of the C2 field; it was
probably Subgroup II. Today Rainer reported a non-group C2 comet in
yesterday's images; it was round and fairly faint, and traveled to the
upper left across the upper right quadrant of the field of view. It has
yet to be included in the tally of SOHO comets.
Brian Marsden noted the possibility that Marsden comet C/1999 P6 may be
returning within the next few days, assuming that it was part of a
fragmentation event that is believed to have occurred around the
November 1993 perihelion passage of a Marsden comet whose split
presumably created C/1999 N5 and C/1999 J6. He further suggested that
C/1999 P8 and P9 may be returning around May 18.
April 22, 2005
Yesterday, Hua Su reported a C3 Kreutz comet; at first, it was up
against the pylon and barely visible, but it became clearer and
brighter once it cleared the pylon. In C2 it was bright, with a
slightly curved tail, and it remained visible for more than 4 hours in
that instrument. Chong Liang also reported a Kreutz comet early
yesterday, in C2. Karl Battams has confirmed them both; the SOHO comet
count is now up to 945.
Rob Matson reported today that Comet 21P/Giacobini-Zinner is faintly
visible in SWAN images; Maik Meyer adds that this would make it at
least magnitude 10.5 - 11.
April 17, 2005
Today Hua Su reported a Meyer comet in C2. It was readily visible, and
slightly elongated. This should be SOHO's 943rd comet, and Hua Su's
25th, all found in an amazing 8-month period.
April 16, 2005
Karl Battams confirmed five comets yesterday, including Bo Zhou's
discovery of April 11, mentioned below. The others were a C2 Kreutz and
a Marsden comet, both found by Hua Su on April 14. The Marsden comet
was in C3, tracking vertically to the left of the Sun. It was then
located in C2 images from earlier in the day. The other two comets were
archival discoveries by Rainer Kracht (bringing his SOHO total to 150);
a Kreutz from September 2000 and a non-group comet from November 10,
2000. Rainer has noted similarities in the trajectories
of this non-group comet and C/2001 T5. On the
MPEC for the discovery,
Brian Marsden notes that the two comets appear to be related, though
Maik Meyer cautions that for many of the non-group comets there are
several possible orbital solutions, and there's no guarantee that the
two are linked.
April 11, 2005
Three C2 Kreutz comets were found in recent days; all were rather
condensed in appearance. Hua Su found the faintest of the bunch, in
images of April 8. It looked like a small, dim, starlike point as it
approached the Sun; it was probably Subgroup II. On April 9, Chong
Liang found a somewhat brighter Kreutz; this was Chong's first SOHO
comet discovery. Today, Bo Zhou reported a Kreutz, condensed, with a
very short tail. Today Karl Battams confirmed the first two of these
comets, bringing the SOHO count to 937.
April 6, 2005
I'm sorry there were no updates for a while; I was out of town. On the
morning of April 4, Xavier Leprette reported a C3 Kreutz comet in
delayed images; it was also visible in C2. It moved below the pylon and
presumably belongs to Subgroup II. This should be Xavier's 98th SOHO
comet, and the project's 935th. On March 28, three Kreutz comets were
found, one each by Maik Meyer, Hua Su, and Bo Zhou. Hua Su's was
visible in both C3 and C2, the others just in C2.
March 23, 2005
SOHO completed its roll, and the LASCO doors reopened at 2200 UT this
evening. The pylon will interfere with comet discovery in C3 for a few
weeks, so most of the Kreutz comets found between now and mid-April are
likely to be only visible in C2. Fortunately, a new "comet storm"
period in which it will be easier to find C2 Kreutz comets is
The SOHO comet count is now up to 931, thanks to seven confirmations by
Karl Battams over the past two days. Two were of comets found by Hua
Su, visible in both C3 and C2, which were found on March 17 and 18,
respectively, bringing Hua Su's comet total to 20. The rest of the
comets were archive claims e-mailed to Karl; one C3 Kreutz from October
1998 was reported by Xavier Leprette, his 97th comet; four other comets
were reported by Rainer Kracht, making him the all-time SOHO
comet-hunting leader with 148 finds. His latest include a Kreutz and a
non-group from 1997 and a Meyer and Marsden from 1996; all were visible
in C3 and the Meyer--from July 3-4, 1996--in C2 also. It is by far the
earliest Meyer comet yet reported. The non-group, the Marsden, and a
non-group from the last batch have already been MPEC'd.
March 15, 2005
It's been a very busy week, cometwise (especially for March, which is
usually a slow period for SOHO comets). Today Karl issued a round of
confirmations, bringing SOHO's total to 924. Michael Oates's comet was
made official, but thanks to 5 discoveries, including 4 archival C3
Kreutz comets from 1997, Rainer Kracht has drawn into a tie with Mike
for the all-time lead with 144 discoveries each. (One of Rainer's
archive finds was a non-group comet; there's a small possibility that
it could be an already-known comet. The astrometry should let us know
for sure.) Rainer's fifth find was a bright Marsden comet from March
10, seen first in C3 and also in C2. Today, Brian Marsden issued MPEC 2005-E87,
which suggests that Rainer's comet, C/2005 E4, is identical with C/1999
N5, which came to perihelion on July 11 of that year. He also suggests
that C/1999 U2 and the aforementioned comet may have split from each
other when near perihelion around Nov. 20-22, 1993, in which case
C/1999 U2 should have a period of about 5.95 years and should reach
perihelion around this October 8.
Among this week's other discoveries, Hua Su found a C3 comet on March
11, then Bo Zhou reported a C3 comet around March 13 while it was near
the very edge of the C3 field. It brightened nicely, and was visible in
delayed C2 images from March 14-15 this morning. Bo Zhou also found a
faint fragment trailing it. (This brings Bo's total to 10.) On March
14, Xavier Leprette found a faint C2 comet, probably Kreutz Subgroup II
(it came from below where most of the Kreutz comets have been entering
C2). This is Xavier's 96th SOHO comet. Kazimieras Cernis also reported
it in C3, though it was extremely faint and I couldn't really make it
out. I did find a C2 comet this morning; it was entering C2 on the
13:36 image (the first after a gap), and when I saw it in the next
image I reported it. Xavier then reported a comet in C3 from earlier
images, but apparently it was the same as my comet.
March 7, 2005
Yesterday, Michael Oates reported a faint, diffuse, tailed comet in C2,
the first Kreutz comet to be found in C2 this year. It was only visible
in about 4 positions, so it may be difficult to confirm; Karl is
submitting the astrometry to Brian Marsden. A solar storm (CME)
hindered its ability to be found in C3.
February 27, 2005
Yesterday, Bo Zhou found two C3 comets. The first was faint; it
traveled along the edge of a coronal streamer. The second one, that
followed the first by about 12 hours, was found near the very edge of
the C3 field. It became rather bright, and showed a straight, thin
tail. It was also visible in C2. This brings SOHO's tally to 913.
February 24, 2005
Yesterday, Hua Su found a non-group comet, obvious though not bright,
in delayed C2 images. Xing Gao also reported it, less than a minute
later. The comet cut upward across the lower right corner of the field.
It is SOHO-911; Karl Battams confirmed it and the previous two comets
February 22, 2005
Last night, I found a rather faint Kreutz comet, about halfway from the
edge of the C3 field from the Sun. The comet grew a short tail and
appeared as a small streak in some of the images. This morning,
Kazimieras Cernis found another C3 Kreutz comet, slightly brighter than
mine and more stellar in appearance. It faded out abruptly. These
should be SOHO-909 and 910.
February 13, 2005
Today, Rainer Kracht found a non-group comet in delayed C2 images from
February 12-13. The spherical comet brightened as it arced to the upper
left across the lower left corner of C2. This is Rainer's 139th SOHO
February 7, 2005
This morning, Xavier Leprette reported a Kreutz comet near the very
edge of the C3 field, in delayed images. The comet developed rapidly,
becoming teardrop-shaped and quite bright for a SOHO comet. It is now
about halfway across the C3 field. This is Xavier's 95th comet, and
February 4, 2005
Karl Battams has now confirmed the four comets mentioned yesterday and
given them SOHO numbers. Xavier's archive is SOHO-903, Bo Zhou's and
Hua Su's Meyer comets are 904 and 905, respectively, and Hua Su's C3
Kreutz is SOHO-906.
Rainer Kracht's discovery of SOHO-900 is featured in a
news note from Sky & Telescope
that appeared on the magazine's Web site on February 1.
February 3, 2005
In the past few days, several SOHO comets have been confirmed (though
not "in red ink"), bringing SOHO's tally to 906. On January 30, Bo Zhou
reported a faint Meyer-group comet in C2 images. On February 2, Hua Su
found another faint C2 Meyer comet in delayed images from earlier that
day and--less than an hour later--a very faint C3 comet, also in
delayed images. Today, Karl Battams confirmed an archival C3 Kreutz
comet found by Xavier Leprette in images from March 5, 1997. This is
Xavier's 94th SOHO comet find.
January 28, 2005
Karl Battams confirmed two new comets today, bringing SOHO's total up
to 602. On January 25, Kazimieras Cernis found an extremely faint
Kreutz comet in C3. The next day, Xavier Leprette reported a C3 Kreutz
of average brightness, and rather condensed. Kazimieras's comet was so
faint that Karl Battams submitted the astrometry before confirming it,
just to be sure, so the MPEC with its orbit on it (which also contained
an orbit for my non-Kreutz comet of December 28 and two other
late-December comets) was released at about the same time that Karl
January 25, 2005
The SOHO-1000 Comet Contest has begun. The object is to predict the
perihelion date and time of the 1000th SOHO comet to be discovered; the
winner will be the one whose guess is the closest. It will be open
until SOHO's comet count reaches 960, still some months away. The first
prize will be "a package of goodies that will include the SolarMax DVD,
a SOHO T-shirt, solar viewing glasses, and a selection of SOHO
materials. Second and third place entries will receive the same package
without the DVD." More information, as well as the entry submission
form, can be found at the SOHO 1000th Comet Contest page
on the SOHO website. Of course, there will be a second, informal
contest among SOHO hunters: who will be the one to discover it? Will it
be in C2 or C3? Large images or black-and-whites? Kreutz, Meyer,
Kracht, Marsden, Kracht2, or non-group? Time will tell.
January 16, 2005
On January 15, Rainer Kracht found a small, faint comet in C3.
Congratulations to Rainer; it would seem to be SOHO-900. It is also his
138th comet, putting him just 5 comets away from tying Michael Oates
for the all-time SOHO comet lead. On January 13, Hua Su found a C3
comet. It looked small and condensed, stellar, as it approached the
Comet 2004 V13 (SWAN) survived its passage through LASCO C3 to emergee
into the morning sky, though greatly dimmed. David Seargent observed it
with a 25cm reflector on January 5, 6, and 7, when he estimated it as
magnitude 11.7, 11.6, and 11.9, respectively. Fittingly, it showed up
better in a Swan-band filter, indicating that it was still an active
comet, producing gas. Michael Mattiazzo, who had been the first to
report the comet in SWAN images, also observed the comet on January 6,
and created this animation of the comet's motion.
January 9, 2005
On January 6, Hua Su reported a fairly faint C3 Kreutz comet, which was
soon after reported by Kazimieras Cernis and David Johnson as well. It
remained small, round, and condensed as it approached the Sun.
January 3, 2005
This morning, Yuan-Tseng Tsai found a relatively faint C3 comet. Karl
Battams confirmed it, as well as numbering it and other recent
discoveries, bringing the total to 897. This includes a comet from
October 4, 2004, faintly visible in both C3 and C2, which Hua Su
reported on New Year's Day. He also gave a faint Kreutz comet found by
Rob Matson on December 28 an X-Comet designation (comet is presumed
real but positional data is inadequate to establish an orbit). Karl
also recently classified my non-group claim of November 8 and another
C3 Kreutz claim from Rob (from December 9) as X-Comets.
January 2, 2005
Early on December 31, I found a C3 Kreutz comet near the edge of the
field. New images weren't available for more than a day, and then only
in trickles, but they showed the comet brighten significantly and grow
a narrow tail of up to 1/3 degree in length as it approached the Sun.
It also showed up nicely in C2.
In 2004, a record number of SOHO comets were found. Excluding my latest
(which reached perihelion in 2005), 171 comets were discovered, about
142 of which were Kreutz sungrazer fragments. The number of Kreutz
fragments has been steadily increasing, from 70 in 1999 to 78 in 2000,
83 in 2001, 106 in 2002, and 128 in 2003 to last year's 142. (These are
approximate totals, and include archival comets in their year of
perihelion rather than discovery.) See my entry for November 28, and
John Bortle's synopsis of Zdenek Sekanina's article on this subject,
for more information. Another notable 2004 occurence was the spate of
Kracht comets found in May, particularly the 6 found between May 12 and
15. And then, the tentative confirmation of the periodicity of several
Kracht and Marsden comets, with periods of 5+ years. Presumably the
coming year will see more Marsden/Kracht comets that can be paired with
earlier appearances in 1999-2000.
E-mail to tonyhoffman [at] earthlink [dot] net