From: Milton Aupperle <milton@outcastsoft.com>

Date: January 31, 2010 6:24:48 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Mars at Opposition

Hi Alan;

On 31-Jan-10, at 5:17 PM, Alan Friedman wrote:

Nice work on a very cold night Jim! I was out for an hour and half and spent about the same amount of time getting the feeling back in my fingers when I was done.

Milton, there is little advantage to an obstruction-free design for imaging. This is not the case with visual observing, of course.

I've read that too.

However I would think that with most SCT's type scopes having 20 to 30% obstruction due to the secondary and hole through the main mirror, you'd be losing a fair amount of light. Even worse for some of those short focal length Newtonian AstroGraph type scopes.

On a side note, does anyone have a link to any web sites that can determine the identity of very faint satellites, given an RA / Dec position at a known date time? I have a very faint (like Mag 20 or fainter) satellite that I captured on 2 frames when imaging IC 417 in Auriga, and I'd like to know what I captured. It looks to be slowly rotating too as the track thickness increases slightly in both frames.

TTYL..

PS: Very nice Mars image for -9°F temps too.

Milton Aupperle