From: Alan Friedman <alan@greatarrow.com>

Date: August 17, 2011 1:35:01 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Commet Garradd C2009 P1

That's excellent Milton - congratulations!

best,

Alan

On Aug 17, 2011, at 2:41 PM, milton_aupperle wrote:

Hi Folks;

Despite the nearly full moon, I managed to image Comet Garradd C2009 P1 last night. I was shooting with the AT8RC scope and guiding on a Mag 8.7 star using the GPUSB for control on my HEQ5 mount. Camera was the Grasshopper binned 2x2 and exposures of 1.25 minutes with Luma filter. Turbulence was awful.

Here is a 31 frame stacked image of the comet (0.83 arc seconds per pixel):

http://groups.yahoo.com/group/Astro_IIDC/files/DSO/Comet_Garradd_C2009P1_20110816_230433_MJA.jpg

I had Astro IIDC align on the comet head, so it found the moving comet core in each frame and pulled them all together. That's why the stars are trails and the head does not move. There isn't much to see except the fainter halo around it.

The compressed source movie (scaled to 50% so it's 1.68 arc seconds per pixel) is shown here:

http://groups.yahoo.com/group/Astro_IIDC/files/DSO/Comet_Garradd_C2009P1_20110816_MJA.mp4

That represents 37.5 minutes of time and each frame is 1.25 minutes apart.

Using the Astrometrics and photometric functionality in Astro IIDC I worked out that it's moving 2.64 arc seconds per minute. The core is a lot fainter than SNP indicates too and I've measured it out as magnitude 10.86. I did not detect and significant (< 0.01 mags change) brightness changes over 37.5 minutes I measured it too.

TTYL..

Milton Aupperle