[AZ-Observing] Re: Changes in 17P/Holmes in Six Hours

I did a photometric measurement on the comet last night.

At UT 25 October 2007 06"00 V= 2.362
This was using delta Per as a comparison star with V= 3.01.

Jeff

At 04:28 -0700 10/25/2007, Tom Polakis wrote:
>My earlier notes for the comet were taken at around 5:30 UT on the 
>25th.  I just took a look at 11:30 UT.  There have been some changes.
>
>Earlier, I would have put the brightness at only a couple tenths 
>brighter than Delta Persei, or 2.8.  Now I have it as not quite 
>midway between Delta and Alpha Persei, which puts it at 2.5, or 
>maybe 2.4.
>
>Through the scope, I have been comparing its by using two 10th (?) 
>magnitude stars within a few arcminutes.  In the earlier view, it 
>was located between these two stars, but has now moved off of this 
>line.  Earlier, I could line up 5 shells between the stars; now I 
>would say that value is closer to 3.  So that shell has grown by 
>between 50 and 100%.  It's late (or early), so I am hoping that 
>these are the same two stars, and I'm not just too tired to make a 
>good observation.
>
>Finally, the fainter "outer halo" that has been mentioned appears to 
>be more easily visible.  The moon's altitude is quite a bit lower, 
>so that could be helping sky brightness.  I don't see anything but a 
>spherical form to this halo, and have not picked up any elongation 
>or faint tail structure throughout the night.
>
>Here's one case where it would be nice to live at a more northerly 
>latitude, where the night would last longer.  But then again, there 
>can't possibly be more comfortable observing weather than what 
>currently exists in southern Arizona.
>
>Tom

-- 
Jeff Hopkins
HPO SOFT
Counting Photons
http://www.hposoft.com/Astro/astro.html
Hopkins Phoenix Observatory
7812 West Clayton Drive
Phoenix, Arizona 85033-2439 U.S.A.
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