2.5 million years ago (roughly)

On Saturday evening, I got out again, and set my sights on M31 this time. Much trickier target. Anyway, I went through the usual setup, level and alignment routing. For some reason, the NexStar failed the first alignment. Odd. Oh, well, I did it again, and this worked fine. Then from experience of trying to focus on my first foray, I slewed to Mirfak, a really nice bright star, swapped the 5mm Ortho (great for aligning the mount), for the 450d and set focus. A quick test shot to check, and yes, spot on, the Mirfak association showing crisp and bright.

So I told the mount to slew to M31. And I was off. First off to determine the maximum exposure time I could use. I started at 30 seconds. Odd, the image showed trails. I reduced to 15 seconds. More trails. Same at 10 and 8. Then I took another 8 and that one was fine... This is so weird. Anyway, I went back up the exposure times, 15, 30, 45, 60, 90 and finally 120 seconds. All were fine. I thought nothing more of it. I setup the timer remote to capture 20 x 120 second expoures, hit go and sat back. Each exposure flashed up on the screen and was looking good. At the end of this, my cheap-bay battery was showing signs of flagging. So I grabbed 3 dark frames and packed away. This took about an hour, and as I had to get up early the following day, this wasn't really a problem.

I downloaded the images, loaded them into DSS and set the stack running. After about 45 minutes, an image popped on screen. I took the 32 bit autosave.tif file, loaded it into PS, did a bit of lp removal, and this popped out.



This puzzled me. I couldn't understand where all those jiggles had come from. Very odd, here's a single image I processed to check, and this one was fine.



Although having said that and looked with more wideawake eyes, the trailing even in that shot can be seen.

I gave up at that point and went to bed.

The following evening, I reviewed all the images throughly and discovered that of the 20, 12 of them were showing signs of trailing in different directions. That was just weird. Then it struck me. The tracking was done purely using the mounts internal motors and unguided. The odd swiggles and trails must have been down to mount tracking errors. Not a lot I can really do about this, as I don't have any form of guiding capability at the moment.

So I restacked just the good frames, and processed the results. Here's what I ended up with. This is about 1000seconds @iso1600, tracked in Alt Az on the NexStar SLT mount, 450d mounted at prime focus on the Vista 80s.



I'm pleased with the end result. I know it needs more data to really get the arms and structure there, but I think I'm at the limits of the capabilities of my equipment getting even this much. Having said that, it was a very useful learning experience and a very worthwhile attempt due to that. I may have a restack again using a few of the only slightly trailed images just to see if I can get any more out of it.