From: "Stanford, Darryl" <stanfordd@smccd.edu>

Date: June 6, 2012 11:13:33 PM MDT

To: "Astro_IIDC@yahoogroups.com" <Astro_IIDC@yahoogroups.com>

Cc: "Stanford, Darryl" <stanfordd@smccd.edu>

Subject: Transit of Venus Image Question

I borrowed our observatory’s DFK 31AF03.AS color camera, coupled it to my old orange tube C8 on a GM8 mount, and used a full aperture Thousand Oaks solar filter.  The images were fed to an older, non-Intel MacBook Pro and an older version of Astro IIDC.  I think the exposures were set at 33.33 ms.  With this setup, I took a 3 hour movie of the transit of Venus.  This was part of an open house ToV event at my college.  

This was the first time I used Astro IIDC.   About 1/2 hour before we opened the doors, I had just tweaked the color balance enough, so that the sun’s color looked reasonably natural.  I noticed a thin, red border around the sun, but could not get rid of it.  We opened the doors and I imaged first contact.  As the transit progressed, I noticed a red border around Venus as well.  I couldn’t stop the imaging and fiddle with the colors, since we had hordes of people.  Anyway, I took a couple of pictures of the screen with my iPod touch and am enclosing them.  ToV1 shows Venus after 1st contact, while ToV2 was taken somewhat later.  What are these red borders and how can I process them out?  It’s somewhat fanciful to think of the border around Venus to represent its atmosphere, but I think it’s much too thick to be that.  Similarly, could the border around the sun represent limb darkening, since we are looking at the sun’s cooler, upper photosphere layer?  

Darryl