[AZ-Observing] Re: Comet Tempel 1 Report
- From: Brian Skiff <Brian.Skiff@xxxxxxxxxx>
- To: amastro@xxxxxxxxxxxxxxx, az-observing@xxxxxxxxxxxxx
- Date: Mon, 4 Jul 2005 13:35:47 -0700 (MST)
I'll have to count myself among those for whom the change in the comet's
appearance was noticeable but modest. I viewed it through a small finderscope
attached to the Lowell 1.1-m. Visiting students Nicole and Kate were using the
telescope to take CCD images with wide- and narrow-band filters throughout the
event. They had been observing the comet on the previous three nights also,
so were familiar with its appearance. The finder (maybe 8x60mm or something
like that---with a lot of spherical aberration) barely showed the comet before
the impact. As others noted, there was no visible flash associated with the
impact, as this surely must have been obscured from Earth by the near-nucleus
coma. Kate was measuring peak-pixel counts on the nucleus and an estimate of
the changing sky background in the images as they took them. Even the first
one centered a couple minutes after the impact was slightly elevated, though
the gradually increasing sky counts (as the comet lowered) made that datum
equivocal. However, within about 20 minutes the peak was 150 percent higher
than the earlier values (above background) despite the increasing sky and the
increasing atmospheric extinction, and presumably worsening seeing, though
despite being at around 3 airmasses the seeing looked both very good and
stable. In the little finder the comet was noticeably brighter, perhaps a
whole magnitude. In the telescopic images the near-nucleus was distinctly more
concentrated as Frank K and others noted visually.
There was, by the way, a major crowd of amateur observers on Anderson
Mesa, occupying just about every spot you could pull a car into and
set up a telescope. Last night was merely another gorgeous bone-dry Arizona
night. By my reckoning, since 21 May, 27 of the 44 nights have been cloudfree
dusk-to-dawn, plus additional partial nights, so there have been few complaints
about clouds. The current lore is that we'll get another week of this before
the monsoon makes another incursion.
\Brian
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