M31 (at last!)

[Clive]

This is the 3th attempt to capture M31 since getting my EQM-35 mount back in September and it's still not perfect.  I must sort out a workflow and stick to it!

1st attempt: forgot to lock the axis clutches so M31 was just out of frame.

2nd attempt: Used the guide scope image for mount alignment and picked the wrong star - not sure whether M31 was anywhere near in that image, I couldn't identify any of the field stars.

Tonight's attempt: Forgot that I had reset the camera mirror lockup to OFF so I had an additional 40 off 1 second exposures.

The image below is the stacked 40 x 180s exposures with no darks (the battery was flat after 2 hours so that's a job for later when its recharged), bias or flats applied.  The focus seems that it could have been better but perhaps that was due the seeing caused my 'dew heater', a disposable hand-warmer attached with an elastic band to the lens (I feel a new DIY project coming on).

Canon EOS200 with Canon 400mm F5.6 lens.

 

[+Bino-viewer]

Not a bad effort there Clive.

Your persistence has paid off, well done 😊

[Bottletopburly]

Well done Clive looks good 😀👍

[+Graham]

That's rather nice. 

 

[Clive]

So that's another lesson learnt - let everything stabilise to the outside temperature before starting imaging!  The camera and lens came out of the house just before I started imaging (in an attempt to prolong the time before everything dewed up - which in hindsight I didn't need to worry about) so slowly dropped from 20C 'ish to 0C over the 2 hour imaging period.  Looking at the DSS information, the FWHM for the first image was 4 pixels and slowly increased image by image to more than 10 pixels with a corresponding drop in the number of stars detected.  Having now acquired the matching darks, I've had chance to play about with the image.  The image below is a stack of the first 24 (of 40) exposures which seems to be the best compromise between reduced star diameter and increased noise.