My Solwind Comets

Solwind 7

Solwind 8

Solwind 9

Solwind 10

I started my search for Solwind comets in early June 2005. Until then I had found 156 SOHO-LASCO comets, 63 of them in archival images (previously unrecognized). Six comets had been found in Solwind images from 1979 - 1985. Even the faintest of them (Solwind 4) was rather conspicious and would have been found within minutes of its appearance in SOHO-LASCO images. I was really confident that there should be other small comets visible in the Solwind images. As the "family tree" of the Marsden group comets suggests, there should be a moderately bright precursor to the current Marsden comets. Although the Solwind images are of much less quality than the LASCO images, it seemed possible to find precursors of the current Marsden, Kracht or Meyer comets.

When I started the search, I was glad to see stars with mag 4 in the Solwind images. The brightest Marsden/ Kracht/ Meyer comets in the SOHO-LASCO images are about mag 5, a brighter precursor should be at mag 4 or perhaps mag 3. When I had seen all Solwind images in late July 2005, I had not found any Marden/Kracht/Meyer comet. They were not as bright as expected or went unnoticed through one of the data gaps.

I found my first Solwind comet on June 30 in images of 1981 November 20. It was clearly a Kreutz group comet with a short tail.

Ten images stacked and aligned on one of the hot spots (left) and on the comet's head (right).
It was fainter than the previously known Solwind comets. I estimated it's brightness as mag 2 - 3. Karl Battams provided useful details of the Solwind images from Neil Sheeley and Don Michels (from the "Solwind gang"). Finally, I tried to get rough positions in R.A. and Decl. My attempt can be seen here. Brian Marsden was able to derive a Kreutz group orbit from these positions and put the material on the new SOLWIND comet on IAUC 8566 (2005 July 12).

Only a week after IAUC 8566 was out, I found the next comet on July 19 in Solwind images of 1983 July 07.

left: 15 images (3 series of five images) stacked and aligned on one of the hot spots.
right: Five images stacked and aligned on the comet's head.
This Kreutz group comet is of similar brightness as the previous one (mag 2 - 3). It shows only a very faint tail.

Three days later, I found another small Kreutz group comet on the evening of July 22 in Solwind images of 1984 August 22/23.

The comet fadet rapidly after the first set of images (shown above), but was faintly visible also in the next set of five images. This is truly the faintest of all Solwind comets until now. I estimate it's brightness in the first images as mag 3.

These latest two Kreutz group comets found in Solwind images were put on IAUC 8573 (2005 July 25).

The next morning after I had found Solwind-9, I looked at the images of 1984 September. I found (July 23) a starlike object in the images of 1984 September 15 and tried to check it's identity with GUIDE 8. But there was no bright star in the field of view. The next images showed that it moved to the left (eastern) side of the images, just opposite to the movement of the stars. This has to be a planet like Mars or Saturn in conjunction with the Sun, but GUIDE 8 said that these planets were too far away from the Sun at this time. The object in question was rather bright (attaining mag 1-2) and could not be an asteroid.

15 images stacked and aligned on one of the hot spots.
This was clearly a non-Kreutz comet. Karl Battams noted that it was possibly visible also in SMM C/P images, but we were out of luck here. The comet was outside of the much smaller SMM C/P field of view.

The Solwind image is enlarged three times (300 %), the SMM C/P image ( from 1980 April 11) is scaled down to 51% and rotated to match the orientation of the Solwind image(s). The arrow head at the Sun's center points to solar North.

This comet was announced on IAUC 8583 (2005 Aug 13).

Orbital Elements of all Solwind Comets

Peri/Node/Incl 2000.0
n: number of positions
arc in days

Orbital elements for Solwind 1-6 are taken from Marsden, B.G.: The Sungrazing Comet Group II. AJ 98, 6, pp. 2306 - 2321, 1989 and precessed to 2000.0.
Orbital elements for Solwind 7-10 are from IAUCs 8566, 8573, 8583.

Magnitudes are from IAUCs or my own estimates.