M13 (3-18-2010)

It was 4 am. M101, which I had been shooting, was crossing the meridian. I could flip the whole scope around and shoot another 2 hours on M101, or I could quickly move the scope over to something just emerging from the trees and take two hours on that. It would have to be something I could find easily, as I was pretty tired. So, here again is the object I've practiced most on: M13.

To do something interesting, I took 10-minute subs. There is some flexure between guidescope and the 80ED, and you see it in this image as slight flaring on the bottom left of each star. It's not much, but it's clearly something to worry about. However, the 10-minute subs gave a much better histogram (all colors moved off the left side) than the 6-minute subs I used for M101. The SXVF-H9C needs at least 10 minute subs, I think, which means I either have to guide off-axis or get a better guiding system.

This is 13x10' through the ED80 with the WO 0.8x II ff/fr, Celestron LPR filter, guided on the Tak EM-10 with a DSI Pro through an AT66ED. Processing was done in Nebulosity and PS CS3.

Here is a smaller version. Shrinking the image makes the guiding error less noticeable: