My Search for SOHO Comets

When I was in my mid-teens, a few years after 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 in the 1970s when I first read the article, that someday 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 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.

My SOHO Comet Discoveries (109 to date)

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