SOHO/Near-Sun Comet News and Views
December 22, 2007
Congratulations to Rainer Kracht on becoming the
first to find 200 SOHO comets. A faint Marsden comet he reported
yesterday was his 200th. This was the first Marsden comet since March
2006 and the 31st overall (according to the list on the Sungrazer
Web site, although some may be reappearances of previously reported
objects, as Marsden comets are believed to be periodic, with periods of
about 5.5 years). As for the other low-inclination new comet group,
this one discovered by Rainer himself, there hasn't been a new Kracht
comet in the past two years. Rainer has proposed that as many as 7
Kracht comets seen in 2002 may return over the next 6 months, between
February and July 2008, though some may be too faint to be seen in
Today, Arkadiusz Kubczak reported a moderately bright C3 Kreutz. Arek's
comet, which approaches the Sun on a trajectory slightly to the left,
or clockwise,of most Kreutz comets at this time of year, is probably
Kreutz Subgroup II, akin to the Great Comet of 1882 and 1965's
Ikeya-Seki. On December 20, Shihong Yuan reported a C2 Kreutz in
yesterday's (UT) images. It was well seen, fairly spherical and
condensed. Hua Su also reported a C2 Kreutz, this one on December 16.
December 14, 2007
The bright Kreutz (SOHO-1414) that I reported on December
12 as it entered C3 has completed its inbound journey, and was
vaporized by its close approach to the Sun.. As it moved through C3 it
brightened and developed a narrow and delicate tail that extended about
a degree. It was well seen in C2, and visible (barely) up to the edge
of the occcultiing disk. Although one of the brightest comets of the
year, it didn't quite rival some of SOHO's most spectacular.
Yesterday, Rob Matson reported a Kreutz, faint in C3 and brighter in
C2. When SOHO-1414 entered C3, it was trailed by a small, elongated
companion, which was first reported by Parrish Collison, his first SOHO
discovery after two years of searching. I noted that the object
appeared to be double, with two distinct components very close
together. When SOHO-1414 was about halfway across the C2 field of view,
I noticed on the opposite side of C2 (the field's upper right) what
appeared to be a Meyer comet, and sure enough, it was confirmed as
such. It should be the 83rd Meyer comet, which would put Meyer-100
about 2 years away.
December 13, 2007
Among the confirmations by Karl Battams yesterday were several milestones--among them
SOHO's 1,400th comet (found by Bo Zhou); Zhangwei Jin's first SOHO
comet and Michal Kusiak's first two; Hua Su's 150th and my 100th .
Rainer Kracht is just one comet away from becoming the first SOHO
hunter to find 200.
I found my 100th SOHO comet on December 10, after 6 1/2 years of
hunting. (I started my search in late June of 2001. It took me 7 months
to find my first SOHO comet, and 2 1/2 years to find my first 10.)
I sort of figured that after finding my 100th I would go into
"semi-retirement" and look much less frequently. I probably still will
do so, but I still had one surprise in store for me. The night after
finding no. 100, I got home late, and noticed what might
have been a comet entering the C3 field. I reported it, and sure
enough, it's a very bright Kreutz comet that's now approaching the Sun.
Shortly after that, I reported a much fainter C3 Kreutz, which Rob
Matson posted 12 seconds before me, and we share credit for that one.
It took me 5 months of searching to find comets 97-99; I found my most
recent 3 in just over a day. Go figure.
December 10, 2007
It's been a busy time for SOHO hunting, now that the
keyhole period is over. When Karl does the next round of confirmations,
I should have at least one SOHO hunting milestone to announce. (Hint:
check out my "My Search for SOHO Comets" page.)
Along with the usual Kreutz comets found in a comet storm period such
as we're in, there have been a couple of other interesting finds. On
December 3, Masanori Uchina reported a non-Kreutz comet that
entered the C2 field from the right of the Sun and cut across the upper
right corner of the field, fading out when it was above the Sun. Today,
Hua Su reported a Meyer comet in C2, the 82nd Meyer comet to be found.
(On November 9, Zhangwei Jin detected a faint Meyer comet; it was
Zhangwei's first SOHO comet.)
Don't forget to look up! Even as Comet Holmes fades, it's still visible
from here in NYC (though no longer a naked-eye object), and is huge and
magnificent from a dark-sky site. I'll soon be adding a page with my
observations and photos of 17P/Holmes. Comet 8P/Tuttle, which I
observed for the first time on December 1, is brightening as it heads
towards a close approach to Earth in less than a month.
November 2, 2007
I'm sorry it's been so long since I last updated these
pages. I've made all the comet totals current. Of course, the big
cometary news is the enormous outburst of Comet 17P/Holmes, which on
and just prior to October 24 increased in brightness within a matter of
days (if not hours) by nearly a millionfold to become an easy
naked-eye object in Perseus--it's been holding steady for the past
week at about magnitude 2.2, and has emitted two expanding, concentric
shells, the outer of gas and the inner of dust.
The big SOHO comet news in recent months was the return of SOHO's first
official periodic comet, P/2007 R5, on September 10-11. The return of
this comet, which is closely related to SOHO another comet (C/2002 R5),
had been predicted by Sebastian F. Hönig.
The comet was found by Bo Zhou, and it reached perihelion within about
4 hours of the predicted time! It had previously reached perihelion on
September 5, 1999 and September 8, 2003, and had been found on those
returns by Terry Lovejoy and Kazimieras Cernis, respectively.
July 17, 2007
Today Karl Battams posted confirmations of SOHO comets
from June and July. They bring the SOHO comet total to 1343. All were
Kreutz, except for a non-group comet found by Hua Su on June 25. Bo
Zhou found 15 of the comets, Karl Battams and Hua Su, 3 each, I found
2, and Alan Watson, Rob Matson, Arkadiusz Kubczak, and Shihong Yuan, 1
each. All of the Kreutz comets over the past 3 weeks have been found in
July 4, 2007
Yesterday, Karl Battams confirmed 14 comets found between May 16
and May 30, with June confirmations yet to come. One was a Meyer comet
found by Hua Su; the rest were Kreutz. Seven of these were discovered
or co-discovered by Bo Zhou, three by me, two by Rainer Kracht, and one
by Maik Meyer.
A C3 comet first reported by Hua Su is approaching the Sun now. The C2
comet storm period is likely over; nearly all of the Kreutz comets
found between now and early to mid-October will be discovered in C3
June 15, 2007
It has been a very busy few weeks. As this "comet storm" period
persists, nearly a Kreutz fragment per day has been found in C2 images.
Many of them, particularly in the past 10 days, have also been visible
in C3. These include an especially brilliant Kreutz comet found by
Shihong Yuan on June 6, which although relatively faint through most of
its passage through C3, developed dramatically as it approached the
Sun, growing a substantial tail that appeared to lengthen even as it
passed through C2, becoming more than a degree long. What's more, it
persisted more than 12 hours after the comet's head passed behind the
occulting disk, presumably until well after the head had vaporized and
the comet had passed perihelion.
May 21, 2007
A few days ago, Karl
Battams posted confirmations of 23 comets, including 16(!) found by Bo
Zhou, including 11 realtime comets found between April 18 and May 15 as
well as 5 archive claims. Confirmations also included a C3/C2 Kreutz
found by Shihong Yuan and several previously mentioned comets: a bright
Meyer comet plus a Kreutz found by Rainer Kracht, Vladimir Bezugly's
Kreutz of April 22, and three C2 Kreutz that I discovered.
Since the confirmations, Bo Zhou has continued his amazing pace of
discovery, finding 5 more Kreutz comets. I found a C2 Kreutz today in
delayed images, and Hua Su reported a rather bright Meyer comet on May
18. It was visible in both C2 and C3.
Meanwhile, on the STEREO front, Alan Watson and others continue to
detect various known asteroids down to fainter than magnitude 13, and
known comets such as 2P/Encke and 29P/Schwassmann-Wachmann 2.
May 6, 2007
Less than a month after Comet 96P/Machholz put on a fine
show in SOHO (and STEREO), another short-period comet passed through
the outer part of LASCO C3. Comet 2P/Encke
entered C3 on April 27 at lower left, below the pylon, and crossed the
bottom of the field from left to right, showing a nice tail. Here is an image of Encke created by Rainer Kracht from STEREO data.
After a slow start, the C2 "comet storm" season that runs from April to
June has picked up. No Kreutz comets were found between April 8 and
April 20, when Rainer Kracht reported a C2 comet. Vladimir Bezugly
found one two days later, and Bo Zhou found three more in the last week
in April, plus another on May 3. Bo had one other C2 comet reporton
April 18 that I suspect is a real comet but wasn't certain enough to
confirm it. (Yesterday, Bo reported three possible members of the great
Kracht comet "storm" of May 5-15, 2004, in which at least 9 Kracht
fragments appeared--one of Bo's new ones has been confirmed so far.)
Rainer Kracht reported a bright Meyer comet in C2 images of May 2; it
was also visible in C3. On May 4, I found two Kreutz comets. both quite
faint, within an hour of each other, one in C3 and one in C2. The C3
comet was later nicely seen in C2, moderately bright and with a
short tail. These were my SOHO comets #90 and 91.
April 8, 2007
Comet 96P/Machholz has
completed its passage across the C3 field of view. This short-period
comet, discovered by American amateur astronomer Donald Machholz in
1986, made its its second passage through the SOHO FOV. It entered C3
on April 1 near the bottom of the field, a bit below the pylon, then
moved clockwise skirting the edge of the field and finally
exiting to the upper left. Comet 96P/Machholz is believed to be
associated with the Marsden and Kracht comet groups as well as the June
[daytime] Arietid meteor shower; the comet is likely their parent body.
On Friday, Karl Battams confirmed six SOHO comets, the six most recent
I mention below (four by Bo Zhou, one by Vladimir Bezugly, and my
Kreutz of March 29 (the only C2-only comet of the group). This brings
the official SOHO count to 1279. Karl mentioned that most if not all of
these comets were observed in the SECCHI HI-1A instrument as well,
thanks to the hard work of people like Alan Watson and Rainer Kracht.
This means, for one thing, that Karl will be able to measure positions
for these comets both in LASCO and at least one STEREO instrument,
doubtless improving orbital accuracy.
Two days ago, Bo Zhou reported a faint Kreutz comet entering C2. It's
easily visible in 3 images, but there's a gap of an hour between
images, and I haven't been able to make anything out clearly in the
images to follow. Hopefully Karl will be able to fsee it in enough
images to officially confirm it. Last night I found a C2 Kreutz
after a gap in images. It was moderately bright and visible in 8 or 9
March 30, 2007
Bo Zhou found two more nice comets in the past
few days.. On March 27, he found a C3 Kreutz comet (likely Subgroup II) traveling up along
the lefthand edge of the occulting disk pylon. It was rather bright and
teardrop-shaped in C2. The next day, he reported a rather bright C2
Meyer comet that was also visible in C3. Yesterday I reported a
Kreutz comet entering C2, elongated and fairly diffuse.
March 23, 2007
Two days ago, Bo Zhou reported a Kreutz comet in C3. Although
near the edge of the field, it brightened and showed a teardrop shape.
It was fairly bright in C2 and looked very nice there as well, trailing
a narrow, straight tail.
March 18, 2007
Terry Lovejoy of Australia, who in 1999 became the first amateur
a comet in online (SOHO) images, has achieved what appears to be
another cometary first. His discovery of Comet 2007 E2 (Lovejoy) is
apparently the first to have been made with a (non-CCD, no telescope)
digital camera, a Canon 350D (Digital Rebel XT) DSLR. Terry joins three
other SOHO comet hunters to have received discovery credit for comets
they've found in the night
sky. Kazimieras Cernis of Lithuania, finder of more than 20 SOHO
comets, discovered three comets visually between 1980 and 1990.
Sebastian Hönig, finder of 39 SOHO comets, discovered C/2002 O4 in
a 10-inch SCT on July 22, 2002.(It was the first comet discovered by a
German amateur since 1946.) Austria's Michael Jäger, who
discovered P/1998 U3 photographically, also was the co-finder of C/2005
P3 (SWAN) in SOHO's SWAN images.
Comet Lovejoy was found at a declination of -50, and visible just to southern-hemisphere observers. By its first published orbit,
the comet will reach perihelion next week at a distance of 1.09 a.u.
from the Sun. By April 20, it will have passed north of the celestial
equator, It will be closest to the Earth around April. 25, at around
0.44 a.u. away, when it may be about magnitude 7.5. and visible
in the morning sky.
It has been a slow time for SOHO comet hunting, with the last comets to
be found a C3 Kreutz by Vladimir Bezugly on March 9, and another C3
Kreutz found by Bo Zhou on March 2. SOHO is emerging from a
keyhole period, but the C3 Kreutz track will soon be occulted by the
pylon (of the occulting disk), so conditions are less than optimal for
finding SOHO comet for the next few weeks--but still, we persist in
February 25, 2007
It has been a slow time for SOHO comets for the past week,
largely due to the keyhole period. (LASCO is now closed, as the SOHO
spacecraft is being flipped.) On February 24, I found a C3 Kreutz
but due to the huge gaps in images, it may not be visible in enough
positions to be made official. Earlier in the month, Karl Battams
confirmed 11 SOHO comets, bringing the total to 1,269. These included
Masanori Uchina's first, a bright one that was found near the edge of
the C3 field. Bo Zhou and Hua Su also found bright C3 comets Bo Zhou's
becoming especially bright. Hua Su also found a C2 Meyer comet,
as well as a C3 non-group comet. Since Karl's confirmations, Hua Su
found two more C3 Kreutz comets and Arkadiusz Kubczak found one; Bo
Zhou also found an archival Kracht comet from May 13, 2004, one of 7
Kracht fragments thatt appeared in a three-day span.
January 27, 2007
Yesterday, Karl Battams confirmed 10 comets, bringing SOHO's
total to 1258. These include Alan Watson's first comet, a Meyer comet
that I found on January 11, and two non-group comets with trajectories
somewhat similar to Kreutz comets. One was found by Luciano Cane and
one by Rainer Kracht; Rainer's comet had previously been classified as
Karl Battams has posted a link to an animation of Comet McNaught
passing through STEREO, as well as still images of the comet in STEREO,
to the SOHO Sungrazer site's news page.
SOHO comet hunters Rainer Kracht, Rob Matson, and Alan Watson have all
been working with STEREO images and identifying asteroids in them.
STEREO images are currently available only in FITS format and require
January 15, 2007
Comet McNaught has finished its passage through the C3 field
of view, and SOHO's image cadence and C3 resolution have returned to
normal. A decrease in the "pixel bloom" as the comet was exiting C3
implies that the object is fading, and visual observations bear this
out. Here's hoping that the comet puts on a fine show for our Southern
January 13, 2007
Comet McNaught (C/2006 P1), the brightest comet ever seen in
SOHO and the brightest to be observed since Ikeya-Seki in 1965, is
currently making its way across the LASCO C3 field of view. It has
become visible with the naked eye in full daylight, although it is very
near the Sun. It's clouded out here in New York, but I was able to see
the comet on four successive nights earlier in the week, a beautiful
sight in binoculars despite clouds and horizon obstructions. I've put
up a page on it.
The last few weeks of 2006 were a for SOHO comet hunting; an average of
a comet a day was discovered during the last 3 weeks of the year. Karl
Battams confirmed most of these in late December to bring SOHO's total
to 1248. All except a Meyer comet found by Rainer Kracht were Kreutz
comets, about half visible in C3 as well as C2. Among the more
intteresting were a pair of relatively bright Kreutz comets, found by
me and Bo Zhou, separated by about 8 hours, which in C3 emerged out of
the Sagittarius star clouds; when they entered C2, three additional
fragments were seen between them. The first SOHO comet of 2007 was
found by Hua Su on January 5; since Karl's last confirmations, about
half a dozen SOHO comets have been found, including the first comet
found by Alan Watson of Melbourne, Australia, who had been monitoring
LASCO since SOHO-1000 days, a Meyer comet that I found a few days ago,
and a possible non-group comet found by Luciano Cane that followed a
track similar to a Kreutz path except that it didn't seem to curve.
E-mail to tonyhoffman [at] earthlink [dot] net