"SOHO-650": The Comet at SOHO's Crossroads



Comet SOHO-650 (center) appeared as a faint smudge,
with a short tail visible on some images.
(Image courtesy SOHO/LASCO consortium.
SOHO is a project of international cooperation
between ESA and NASA.)


I took August 5, 2003 off from work because of a bad cough. It was a gray, gloomy day, and my mood was not helped by some distressing news I’d gotten about the health of a friend. I slept much of the morning; in mid-afternoon, I logged onto SOHO and downloaded the latest C3 (blue) images. On three consecutive frames, starting at 1818 UT, I noticed a faint, moving smudge that might be a comet, might be noise. It was suspicious enough that I measured its coordinates on the image and prepared a report, but before sending it waited for a fourth image to confirm or negate it as a comet. When a new image came up, a bit to my surprise it showed a spot where a true comet would be, so I quickly measured its position and submitted the claim. Less than a minute later, Mike Boschat reported the same object. I now was 99% sure it was real, and the next image clinched it: the first comet I’d found in C3 while still relatively far from the Sun since my very first comet back in February 2002. I watched it develop over the next six hours; it was clearly seen, but never bright. Although apparent on the last image posted that evening (time-stamped 0142 UT August 6), it must have faded abruptly as it was not to be seen on the 0318 image which was uploaded the next morning.

The night before I found the comet, Derek Hammer—the SOHO person in charge of checking comet claims—had posted a farewell message to the Sungrazer website, while confirming some final comets before he left. He indicated that he would not be replaced, and that SOHO’s solar scientists would occasionally monitor the site to confirm comets. About 85 Kreutz comets, dating back to November 2002, have not had accurate positions measured nor been officially announced. Many SOHO comet hunters (including myself) are worried that it may be a long time—if ever—before these and any new comets found in SOHO images have orbits calculated and are officially announced. Four of my discoveries, including the latest (which will presumably be SOHO-650 when and if internally confirmed), are caught in this limbo; only my first two have been announced on IAU/MPC circulars.

Despite the decline of SOHO’s comet program, I intend to continue my search. Although the recognition in having my name mentioned in the circulars and the knowledge I was contributing to our understanding of these comets were both motivating factors, ultimately I look because of my love for comets, particularly sungrazers, and my desire to seek them out. It’s in my blood; someone has to look out for these things, and the fact that SOHO’s budget seemingly no longer supports cometary astrometry should not lessen my thrill in finding them.



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tonyhoffman@earthlink.net