My Search for SOHO Comets

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When I was in myteens, around the time I got interested in astronomy, I found a used copy of the February 1966 National Geographic at a garage sale. The issue, which I still have today, contained an article, "Giant Comet Grazes the Sun", describing the passage of the brilliant Comet Ikeya-Seki just a short distance from the Sun's surface at perihelion, its visibility in full daylight when very near the Sun, and its subsequent long-tailed apparition in the morning sky, particularly for people at southern latitudes. The article also described the discovery of the comet in the words of Kaoru Ikeya and Tsutomu Seki,the two Japanese amateurs who independently found it. Reading this account started a fascination with sungrazing comets of the Kreutz group--of which Ikeya-Seki is one of the most spectacular examples--that continues to this day. Little did I imagine, back around 1970 when I first read the article, that within a few decades we would have computers in our homes that could connect to the latest sources of astronomical data, and that although I would live in one of the most light-polluted cities on Earth, I would actually discover small fragments of these fabled comets on spacecraft photos of the Sun's vicinity taken by SOHO (the Solar and Heliospheric Observatory)--though I have never yet seen a Kreutz comet in the sky as opposed to on a computer screen.

SOHO-1087 approaches the Sun
on January 5, 2006. (Image courtesy
the SOHO/LASCO consortium. SOHO
is a project of international cooperation
between ESA and NASA.)

My SOHO Comet Discoveries (113 to date)

No. Date found (local time) Designation Group Camera MPEC/IAUC Notes
1 February 10, 2002 C/2002 C4, SOHO-390 Kreutz C3 2002-C95 7839 Visible after SOHO came out of “safe mode”; lost in solar storm after 12 hours. Discovery Story + Images
2 June 28, 2002 C/2002 M5, SOHO-474 Kreutz C2 2002-N41 7935 Found in b/w images; I reported it 7 seconds before Rob Matson. Discovery Story + Image
3 December 2, 2002 C/2002 X13, SOHO-564 Kreutz C3, C2 2004-A40
Condensed, no tail. Faint in C3, fairly bright in C2. Discovery Story + Animation
4 April 28, 2003 C/2003 H10, SOHO-600 Kreutz C2 2004-C54 This "milestone" comet had to be tracked through a gap in images to confirm. Discovery Story + Image
5 May 29, 2003 C/2003 K12, SOHO-620 Kreutz C2 2004-G19 A Kreutz Subgroup II comet. Discovery Story + Image
6 August 5, 2003 C/2003 P3, SOHO-650 Kreutz C3 2004-J19 One of an unusual number of C3 Kreutz comets found over a short period of time. Discovery Story + Image
7 August 20, 2003 C/2003 Q1, SOHO-651 Marsden C2 2004-J19 My first (and the year's first) Marsden-group comet. (Its orbit, though, is a bit unusual for a Marsden comet.)
8 November 9, 2003 C/2003 V6, SOHO-688 Kreutz C2 2004-K34 Found in 2 days of b/w images that were released at once. Image and animation
9 November 30, 2003 C/2003 X1, SOHO-698 Kreutz C2 2004-K55 Faint and condensed. Found in b/w images.
10 December 8, 2003 C/2003 X8, SOHO-705 Kreutz C2 2004-L24 Fairly faint and condensed. Found in b/w images.
11 January 15, 2004 C/2004 A3, SOHO-725 Kracht C2 2004-M04 Faint, only visible in ~5 images. Preceded a brighter Kracht comet found by XingMing Zhou by 2 days.
12 January 24, 2004 C/2004 B8, SOHO-731 Kreutz C3 2004-M10 Faint and stellar when found in C3; brightened somewhat and grew a short tail.
13 February 8, 2004 C/2004 C5, SOHO-738 Kreutz C3 2004-M13 Very faint, though with a short tail in several images.
14 February 9, 2004 C/2004 C6, SOHO-739 Kreutz C3 2004-M13 Another faint C3 Kreutz (though slightly brighter than the previous night's comet).
15 February 24, 2004 C/2004 D3, SOHO-742 Kreutz C3 2004-M14 The trailing member of a pair of Kreutz comets (the other discovered by XingMing Zhou ) found near the edge of the C3 field.
16 April 4, 2004 C/2004 G4, SOHO-753 Kreutz C2, C3 2004-M65 Found in delayed images; bright and obvious in C2; also visible in C3 (Lindau images only) against the pylon.
17 April 10, 2004 C/2004 G2 SOHO-754 Meyer C2 2004-H01 Visible in 4 images as it crossed the upper left corner of the C2 field.
18 April 10, 2004 C/2004 G5, SOHO-755 Kreutz C2 2004-M65 Obvious in C2; I found it 3-1/2 hours after SOHO-754.
19 April 19, 2004 C/2004 H8, SOHO-762 Kreutz C2 2004-M66 One of 3 Kreutz comets found in C2 within 12 hours of each other (at the same time the bright Comet Bradfield was crossing C3).
20 May 2, 2004 C/2004 J1, SOHO-766 Kreutz C2 2004-M71 Faint, with a short tail.
21 May 5, 2004 C/2004 J5, SOHO-769 Kreutz C2 2004-M71 Found in b/w images; not too bright, but with a fine tail. I reported it 7 seconds after XingMing Zhou, and we got joint credit for the find.
22 May 7, 2004 C/2004 J6, SOHO-771 Kreutz C2 2004-M71 Very faint and condensed, yet visible in nearly 10 images.
23 May 14, 2004 C/2004 J14, SOHO-778 Kreutz C2 2004-N04 Not too bright but tailed; visible in more than 10 images.
24 May 14, 2004 C/2004 J16, SOHO-781 Kracht C2 2004-N05 One of a flurry of 5 Kracht comets found in 3 days (the others found by Rainer Kracht himself).
25 June 26, 2004 C/2004 L11, SOHO-805 Kreutz C2 2004-P12 A faint Subgroup II Kreutz comet from images of June 15 that had been previously unreported.
26 June 27, 2004 C/2004 M4, SOHO-806 Kreutz C2, C3 2004-P13 The brightest of three Kreutz comets I found in delayed b/w C2 images of June 27. Also visible faintly in C3.
27 June 27, 2004 C/2004 M7, SOHO-807 Kreutz C2 2004-P13 With a substantial tail but very washed out; on its last legs.
28 June 27, 2004 C/2004 M5, SOHO-808 Kreutz C2 2004-P13 The lead member of a close comet pair. I was the first to report it as a likely double, to the Yahoo Sohohunter list, but didn't give positions, rather saying "with a secondary component a few pixels below the positions I reported." Xavier Leprette was given credit for finding the second component.
29 August 15, 2004 SOHO-828, C/2004 Q7 Kreutz C3 2004-T66 Moderately bright and condensed; stayed in view for a full day, as it was found near the edge of the C3 field.
30 August 19, 2004 SOHO-829, C/2004 Q3 Kreutz C3 2004-T66 Found near the edge of the C3 field; similar to the previous comet in appearance and behavior.
31 August 25, 2004 SOHO-832, C/2004 Q6 Kreutz C3 2004-T66 Easily visible though not bright; fairly condensed, and occasionally showed a short tail.
32 October 13, 2004 SOHO-844, C/2004 T7 Kreutz C3, C2 2004-X23 Found near the edge of the C3 field when still quite faint, it brightened nicely and grew a short tail. Also well seen in C2.
33 October 25, 2004 SOHO-852, C/2004 U9 Kreutz C3, C2 2004-X24 Found halfway across the C3 field, it remained condensed as it approached the Sun, and appeared small, moderately bright, and spherical in C2.
34 November 3, 2004 SOHO-856, C/2004 V6 Kreutz C2 2004-X72 Quite faint, small, and round; found in a combination of color (1024 x 1024) and b/w (512 x 512) images.
35 November 3, 2004 SOHO-857, C/2004 V7 Kreutz C3, C2 2004-X72 Found within 45 minutes of SOHO-856. Very faint and difficult in C3; an obvious small, round spot in C2
36 November 8, 2004 SOHO-861, C/2004 V11 Kreutz C2 2004-X74 Faint, small, and round; had been missed by other hunters, no doubt because of interference from a solar storm.
37 November 16, 2004 SOHO-864, C/2004 V15 Kreutz C3, C2 2004-Y37 A Kreutz Subgroup II comet. Approached the Sun from about 15 degrees to the left (clockwise) of the point where most Kreutz comets come from this time of year.
38 November 16, 2004 SOHO-865, C/2004 W1 Kreutz C2 2004-Y37 Found in a combination of b/w and color images
39 November 24, 2004 SOHO-870, C/2004 W7 Kreutz C3, C2 2005-A12 First seen in realtime C3 b/w images; developed quickly and displayed a narrow, delicate tail up to ~1/3 degree long as it neared the Sun.
40 December 4, 2004 SOHO-877, C/2004 X5 Kreutz C2 2005-A13 Round and fairly faint yet visible in 10 images; partially obscured in early images by the timestamp.
41 December 6, 2004 SOHO-878, C/2004 X6 Kreutz C2 2005-A40 Quite faint and quickly becoming diffuse, yet visible in 12 images; partially obscured in early images by the timestamp.
42 December 28, 2004 SOHO-894, C/2004 Y10 non-group C2 2005-B62 Descended almost vertically along the extreme lefthand edge of C2; visible in nearly 30 images. Perihelion distance was .0322 AU; see link to MPEC for other orbital elements.
43 December 31, 2004 SOHO-896, C/2004 Y12 Kreutz C3 2005-C38 Found while still near the edge of the C3 field; became fairly bright, with a narrow of tail up to 1/3 degrees in length. Well seen in C2 (on January 1, 2005), with a tail up to 1/4 degrees.
44 February 21, 2005 SOHO-909, C/2005 D2 Kreutz C3 2005-G40 Found after a gap in images. Faint, with a short tail; streaky-looking.
45 March 15, 2005 SOHO-919, C/2005 E8 Kreutz C2, C3 2005-G93 Obvious, with a short tail; presumably the same comet reported later in C3 by Xavier Leprette and myself (but unfortunately there was a large image gap when it would have been at its best in C3).
46 April 24, 2005 SOHO-946, C/2005 H5 Kreutz C2 2005-K44 Obvious, with a short tail; there was speculation it might be the same as a C3 object reported earlier by Bo Zhou, but it turned out not to be.
47 May 8, 2005 SOHO-953 Kreutz C2, C3 to come Obvious, teardrop-shaped comet, first reported in a mix of color and b/w C2 images. Also faintly visible in C3.
48 May 15, 2005 SOHO-960 Kreutz C2 to come Very faint, round comet seen entering C2. Only visible in ~4 images.
49 May 20, 2005 SOHO-963 Kreutz C2 to come Faint Kreutz comet, visible in ~7 images. Possible fragment trailing the comet, but only visible in first 3 images.
50 June 5, 2005 SOHO-971 Kreutz C2 to come Rather faint and round; I reported it 5 seconds after Sebastian Hönig, who shares credit for it with me. There was only one normal C2 image per hour, so it was only visible in 4 or 5 such images.
51 June 5, 2005 SOHO-972, C/2005 L7 Kreutz C3, C2 to come Found when more than halfway across the C3 field, it brightened nicely as it approached the Sun, and was visible until it passed behind the occulting disk. Quite bright in C2, trailed by a fragment found by Bo Zhou.
52 June 12, 2005 SOHO-977, C/2005 L12 Kreutz C2, C3 2005-N76 Found in delayed C2 images, where it was round and moderately bright. Also visible in C3. This comet was on a "Sunstriker" orbit with a perihelion point actually inside the Sun, meaning it would have collided with the Sun had it not undoubtedly vaporized first.
53 June 12, 2005 SOHO-979, C/2005 L14 Kreutz C2 2005-O26 Very faint and indistinct, yet visible in more than 20 images.
54 June 20, 2005 SOHO-983, C/2005 M4 Kreutz C2 2005-O26 Round and diffuse, with a trace of a tail, and visible in nearly 25 images. I reported it 24 seconds before Hua Su.
55 July 23, 2005 SOHO-996, C/2005 O4 Kreutz C3 2005 Q04 Found halfway across the C3 field. Quite faint, small, and starlike, and slow to brighten.
56 July 26, 2005 SOHO-997, C/2005 O6 Kreutz C3, C2 2005 Q04 Found nearly halfway from the edge of the C3 field. Round and fuzzy at discovery, brightened, and was briefly visible in C2, where it quickly faded.
57 July 26, 2005 SOHO-998, C/2005 O5 Meyer C2 2005 Q04 Found in a noisy section of the C2 images. Brightened somewhat as it climbed towards the edge of the field.
58 August 10, 2005 SOHO-1001, C/2005 P4 Kreutz C3 2005-T55 Found halfway from the edge of the C3 field. Faint, round, and fuzzy at discovery.
59 August 23, 2005 SOHO-1006, C/2005 Q2 Meyer C2 2005-R06 Although moderately bright, it was a difficult find because the C2 field was dotted with noise from a particle storm.
60 August 30, 2005 SOHO-1011, C/2005 Q3 non-group C2 2005-R06 Faded rapidly after entering C2. It followed a trajectory similar to that of a Marsden comet except slightly below the nominal track, and moving perhaps 1.5 times as fast. I wondered if it might be related to C/2003 Q1 (SOHO), whose speed and trajectory seemed similar to it, but the orbit indicates that it is a sporadic, non-group comet.
61 October 15, 2005 SOHO-1031, C/2005 T11 Kreutz C3, C2 2005-X52 Appeared abruptly about 1/4 of the way in from the edge of the C3 field. Brightened and developed a thin tail that lengthened as it approached and passed behind the C3 occulting disk. Showed up nicely in C2 as a small, bright, round, slowly fading spot that trailed a narrow tail. Nearly 3/4 degree of tail were still visible once the comet passed behind the C2 occulting disk. Likely a Kreutz Subgroup II comet.
62 November 19, 2005 SOHO-1053, C/2005 W10 Kreutz C2 2005-Y15 Quite faint, diffuse, with a short tail.
63 January 3, 2006 SOHO-1087, C/2006 A5 Kreutz C3, C2 to come Found near the edge of the C3 field, this comet became very bright, with a tail of a degree or more in length as it climbed through eastern Sagittarius towards the Sun. It was still bright as it entered C2; later, its tail extended from the edge of the field to the occulting disk as the much faded comet disappeared behind the disk. Easily my brightest SOHO comet find.
64 January 10, 2006 SOHO-1088, C/2006 A6 Kreutz C3 to come Stellar in appearance and inconspicuous, yet visible in more than 20 images.
65 March 14, 2006 SOHO-1112, C/2006 E4 Kreutz C2 t/k Faint, elongated or with a short tail.
66 March 22, 2006 SOHO-1116, C/2006 F6 Meyer C2 t/k Visible in nine images as it moved to the upper right across the upper left corner of the C2 field. Obvious, though not bright, and slightly elongated in the direction of motion.
67 March 25, 2006 SOHO-1117 Marsden C2 t/k Visible in eight positions crossing the upper left corner of the C2 field. Fairly faint.
68 April 11, 2006 SOHO-1120, C/2006 G2 Kreutz C2 t/k Faint, round, and quite diffuse. Visible in nearly 10 positions
69 May 5, 2006 SOHO-1128, C/2006 J2 Kreutz C2 t/k Obvious, with a short tail.
70 May 10, 2006 SOHO-1133, C/2006 J7 Kreutz C2 t/k The leading (and slightly brighter) member of a very close pair (with SOHO-1134) of small, round C2 Kreutz comets that no doubt had recently split in two.
71 May 10, 2006 SOHO-1134, C/2006 J8 Kreutz C2 t/k The trailing (and slightly fainter) member of a very close pair (with SOHO-1133) of small, round C2 Kreutz comets that no doubt had recently split in two.
72 May 11, 2006 SOHO-1136 Kreutz C2 t/k Small, rather faint, round, and diffuse; possible short tail.
73 June 10, 2006 SOHO-1163 Kreutz C2 t/k Small, faint, round, and diffuse. Visible in 6 or 7 positions.
74 June 19, 2006 SOHO-1166 Kreutz C2 t/k Found in delayed images. Obvious and fairly condensed; visible in nearly 20 images.
75 July 17, 2006 SOHO-1174 Kreutz C3 t/k Faint and slightly elongated.
76 September 11, 2006 SOHO-1187 Kreutz C3 t/k Already obvious when found near the edge of the C3 field after an image gap. Only visible in 7 images due to huge image gaps due to SOHO's keyhole period and flip. There's no saying how bright it may have gotten as it approached the Sun.
77 October 15, 2006 SOHO-1201 Kreutz C3, C2 t/k Fast moving, faint and teardrop-shaped in C3, nicely tailed in C2
78 October 15, 2006 SOHO-1202 Kreutz C2 t/k Faint and round.
79 October 20, 2006 SOHO-1205, C/2006 U10 Meyer C2 t/k Fairly faint, elongated.
80 November 7, 2006 SOHO-1218 Kreutz C2 t/k Tailed, diffuse, obvious but faint.
81 November 19, 2006 SOHO-1224 Kreutz C2 t/k First visible after a gap in images. Tailed, diffuse, obvious; the leading member of a pair separated by just over an hour.
82 November 19, 2006 SOHO-1225 Kreutz C2 t/k Round and fairly condensed; the trailing member of the aforementioned Kreutz pair.
83 December 15, 2006 SOHO-1235 Kreutz C2 t/k Faint, tailed, diffuse, fairly large. I reported it 6 seconds before Rainer Kracht, who gets joint credit for it.
84 December 20, 2006 SOHO-1240 Kreutz C3, C2 t/k Climbed out of the Sagittarius Milky Way as it approached the Sun. Stellar and fairly bright in C3; round with a hint of a tail in C2. Followed 8 hours later by a comet of similar brightness found by Bo Zhou.
85 December 21, 2006 SOHO-1243 Kreutz C2 t/k One of a cluster of 3 small fragments that trailed SOHO-1240 by about 3 hours.
86 December 22, 2006 SOHO-1245 Kreutz C3, C2 t/k Fairly faint and stellar in C3; obvious, condensed, and elongated in C2.
87 January 11, 2007 SOHO-1256, C/2007 A6 Meyer C2 t/k Visible in nearly 20 images as it cut across the upper left corner of the C2 field in delayed images.
88 March 29, 2007 SOHO-1279 Kreutz C2 t/k Elongated, somewhat diffuse, and visible in about 7 images.
89 April 7, 2007 SOHO-1280 Kreutz C2 t/k Obvious after a gap in images, visible in ~9 images, slightly elongated.
90 May 4, 2007 SOHO-1289 Kreutz C3, C2 t/k  Faint and hard to discern in C3; rather bright, elongated with a short tail in C2
91 May 4, 2007 SOHO-1290 Kreutz C2 t/k Quite faint, elongated in early images, visible in ~7 images altogether. Found less than an hour after my previous comet.
92 May 21, 2007 SOHO-1309 Kreutz C2 t/k Visible in delayed realtime images; found after a gap in images.
93 May 24, 2007 SOHO-1313 Kreutz C2 t/k Faint; elongated or with a short tail
94 May 31, 2007 SOHO-1316 Kreutz C2 t/k I reported this faint Kreutz two seconds after Bo Zhou
95 June 14, 2007 SOHO-1327 Kreutz C3, C2 t/k Globular and slightly diffuse in C3; moderately bright in C2
96 June 24, 2007 SOHO-1330 Kreutz C3, C2 t/k Found when halfway across the C3 field; obvious and teardrop-shaped in C3; bright when entering C2, with a narrow, faint tail; faded rapidly
97 October 10, 2007 SOHO-1367 Kreutz C3, C2 t/k Found in delayed images; I reported it 11 seconds after Bo Zhou. Preceded by a fainter comet 1 hour ahead of it.
98 October 30, 2007 SOHO-1383 Kreutz C3, C2 t/k Apparent though not bright in C3; small and spherical in C2
99 November 25, 2007 SOHO-1403 Kreutz C2 t/k A faint Kreutz from images of November 23 that had been overlooked, probably  because it was tracking well to the left of other recent C2 Kreutz comets (it was a Kreutz Subgroup II fragment; see my notes below), and amid the timestamp numbers.
100 December 10, 2007 SOHO-1413 Kreutz C3, C2 t/k Faint in C3; obvious and with a short tail, in C2.
101 December 12, 2007 SOHO-1414 Kreutz C3, C2 Easily visible as it entered the C3 field; steadily brightened and developed a narrow, delicate tail. Very bright in C2, visible up to edge of occulting disk; also visible in SECCHI COR2 and HI images.
102 December 12, 2007 SOHO-1415 Kreutz C3, C2 Reported 12 seconds after Rob Matson. Faint in C3
103 December 14, 2007 SOHO-1419 Meyer C2 Visible opposite SOHO-1414 in C2, in about 12 images
104 February 19, 2008 SOHO-14?? Meyer C2 Visible in 7 images before a data gap
105 June 15, 2008 SOHO-1494 Kreutz C3, C2 Found when halfway across the C3 field; faint, slow-moving, with a short tail at discovery; brightened rapidly and showed a narrow, straight tail; very bright in C2 with a  tail of about a degree long that lingered after the comet passed behind the occulting disk; also visible in SECCHI COR1, COR2 images.
106 June 27, 2008 SOHO-1501 Kreutz C2 Faint and rather diffuse; visible in about 7 images
107 June 28, 2008 SOHO-1502 Kreutz C2 Obvious, diffuse, visible in about 11 images
108 July 3, 2008 SOHO-150x Kracht C2 The presumed return of C/2002 S7, previously observed as C/1996 X4; stellar in appearance;  seen as it entered C2 to the right of the Sun and approached the Sun.
109 July 6, 2008 SOHO-150x Kreutz C2 Faint and triangular-shaped; presumably a fragment of a brighter comet found by Hua Su, which it followed by about 2.5 hours.
110 August 9, 2008 SOHO-15xx Kreutz C3, C2 Found after a gap in images; moderately bright in C3, with a short taill; diffuse and tailed in C2.
111 October 11, 2008  SOHO-1541 Kreutz C3, C2 Very faint in C3; tailed and diffuse in C2.
112 October 20, 2008 SOHO-1550 Kreutz C2 Very faint, diffuse, large, tailed.
113 January 30, 2009 SOHO-1607(?) Kreutz C3 Found after a gap in images, using regular + b/w images. Faint but obvious; stellar in appearance.

The comets above (except perhaps for the most recent) have been internally confirmed by the SOHO team. Please note that official credit for the discovery of SOHO comets goes to the SOHO spacecraft rather than the individuals who find them, although the finders are listed on the discovery bulletins and on the Sungrazer Web site. There is usually a few weeks delay between confirmation and official reporting. A list of SOHO comets that have been assigned numbers by the SOHO team but are pending official announcement can be found here.

Nearly all my discoveries of Kreutz sungrazer fragments belong to Subgroup I, a group whose most prominent member is the Great Comet of 1843. They have extremely small perihelion distances, generally 100,000 km or less from the solar surface, or around .005 au from the center of the Sun. C/2005 L12 and C/2006 A5's perihelion distance would have actually placed these comet inside the sun when at their closest, though they likely both vaporized before their scattered molecules impacted the Sun. (The latter comet was among the brightest Kreutz comets to be seen in SOHO.) C/2003 K12, C/2004 L11, and C/2004 V15 belong to Subgroup II, which includes Ikeya-Seki and the Great Comet of 1882. Their perihelion distances are about 500,000 km from Sol. C/2004 A3 and C/2004 J16 belong to the Kracht group of near-Sun comets, and C/2003 Q1 is probably related to the Marsden group; comets from both groups have perihelia averaging about 7 million km from Sol, and they are believed to be short-period. C/2004 G2, C/2005 O5, and C/2005 Q2 belong to the Meyer group of near-Sun comets, which have perihelion distances of about 5.2 million km. They have highly inclined (~71 degrees) orbits, and appear to be long-period. C/2004 Y10 and C/2005 Q3 are sporadic or non-group comets, belonging to no known comet group. While all of the Kreutz comets found in SOHO have been vaporized by their close passage to the Sun, it is believed that many of the comets from the other groups survive and continue to orbit the Sun.

My SOHO X/comets

X/comets are deemed probably real by the SOHO team, but they are unable to be confirmed due to lack of adequate positional data.

May 31, 2003

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