From: Willie Strickland <cwskas@earthlink.net>

Date: December 10, 2009 11:11:05 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Occultation a bust for me

I am attaching a jpg of the 5 frames.  Diotima is on the left and TYC 1252-803-1 is on the right.  North is up and east is left.  It was pretty cool to see Diotima converge on the star.

I needed 30 sec exposures and a clear filter using the main science camera (13 micron pixels, 512x512) to get these frames.  Diotima was estimated at 11.9 mag & TYC 1252-803-1 is listed as 10.9 mag.  The occultation was expected to last a maximum of 15.5 seconds and produce 1.4 mag drop in the star.

I used Nebulosity to measure the distance.  In the first frame I measured 110 pixels or 53.9 arcsecs.  The last frame I measured 11 pixels or 5.4 arcsecs.  That is 38.5 arcsecs in 1:12:10 which I calculate as .6736 arcsecs per minute.  Someone else will have to figure out how fast Diotima was moving.  :-)

I am glad the scope tracked well.  I could only see the targets on occasion.  I just kept taking images, hoping it would clear in time.  At least I got some experience.

Willie

   05:49:48 UTC Dec 6, 2009         06:10:27 UTC Dec 6, 2009         06:30:22 UTC Dec 6, 2009

   07:17:50 UTC Dec 6, 2009         07:21:58 UTC Dec 6, 2009