Disappearing comet fragment (7 May 2006)

by Pentti Kanerva

Twice during the last week the nightly blanket of clouds over the Peninsula kept me from looking for the fragments of the comet 73 P Schwassmann-Wachmann 3. Not so last night. I took the scope out soon after 2am (pdt) as the Moon was making its way down to the trees. There were strings of high clouds, not thick enough to block the stars, and even they dissipated in an hour or two. I hoped to see the two brightest fragments, C and B.

C is on its way to the Ring Nebula in Lyra, so I started with a quick look there. My chart showed C to be about one day away to the west and passing by a bright star west of Lyra's Beta, so I pointed the scope there and saw an unmistakable cloud of dust just west of the star. That was too easy; I'll return for a longer look after chasing after fragment B.

B was more of a challenge and had me scanning along its track for a good while before I detected a faint glow next to some faint stars. In 20 minutes or so it moved noticeably relative to the stars, so that must be B. I felt the presence of Charles Messier.

Now back for a closer look at C, but I could not see C! I made sure to be looking in the right place. Where did it go? My confidence returned when C began appearing east of the star. While in line with it, the star's brightness overwhelmed the faint glow of C. The eye is so easily fooled. I kept looking at the show for 20-30 minutes as the two separated, changing eyepieces, being amused, then packed around 4am.

Here are some stats for the coincidence from CalSKY:

The bright star:
SAO 67164, HD 172044, FK5 67164, TYC 2641-2396-1
RA=18:36:52.2 DE=+33:28:06.5 5.4m

Comet Schwassmann-Wachmann (73P):
RA=18:36:52 DE=+33:26:54 7.0m 7.05.2006 6:12:00.0

My timing of the coincidence is more like 10:20 UT, so the comet is running four hours behind schedule. At this rate it will be on top of the Ring Nebula tomorrow (8.05.2006) around 3 UT. European imagers, take note!

Posted on sf-bay-tac May 07, 2006 16:18:19 PT
Converted by report.pm 1.4 Jul 02, 2006 15:30:31 PT

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