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M42 19/12/2014

Andy Mac


Like Pete Hill, I ventured out on Friday night as it was so clear although I was also worried about the strong wind blowing. Luckily my decking was fairly well protected from the worst of it and my pier is set quite low, too low really but quite an advantage in windy weather. I didn't get outside until about 19:30 and I had decided to try my 5d with my Skywatcher Evostar 120mm. I have only used this combination for some solar and lunar photography before and was quite excited to try it on some deep sky, with M42 being my primary target. However, M42 does not clear the trees until quite late so I planned to get some shots of M45 while I was waiting.


I had removed my 400mm canon lens from the one side of my dual mounting bar and fitted the Skywatcher and managed to find the Eos adapter to join the camera and telescope. Added to the fact that the back door has been blocked by the parrot cage to make room for the Christmas decorations everything was taking twice as long to take outside through the front door and back gate. To top it all I had forgotten that the last time I had been out the gears on one axis had become unmeshed and was not driving correctly, this took at least half an hour to sort out. I managed to get my first blurry image of M45 at least an hour after I had first set foot outside.


By this time M42 was not far from clearing the conifers next to my decking at around 20:30, a lot better than a few weeks ago before I had cut them down to size and had to wait until past midnight almost to get a clear view. I had only managed one or two shots of M45 and had not quite nailed the focus yet. So a couple more shots of M42 of varying exposure length to achieve focus and I was starting an imaging run. Although I had the guide scope set up on the other side of the mounting bar I decided I didn't want to waste any more time getting my laptop outside and calibrating the guider so imaged unguided at 90 seconds. I set it all going and went back in to watch some telly which was around 21:10!!


I went back out again about 10:25 to check how things were coming along and found that the battery was about gone so had to change it. I checked the image and found that the view had moved so that M42 was no longer near the centre and I had to move it back. I took my last image of M42 at 23:01 and decided to try a few images of the flame nebula. This required a more lengthy slew which started off fine but soon ground to a noisy halt. I thought this was due to the earlier problem with the gears but after a few more tries I realised that I had not balanced the rig at all with the extra weight of the scope so had no counter weight on the shaft which I have not needed with just my camera lens on. After adding a weight everything move nicely again. However, on inspecting my files after getting back inside quite few of the M42 images were useless due to trailing, most probably due to the unbalanced rig, and this had caused the movement of the field of view as well.


I still got about an hours worth of useable data and have attached one of the processing attempts. This is cropped slightly to show the areas of interest. You can see some evidence of the mixed fields in the background but the actual nebulae don't look too bad and I will be keen to get back out when it is clear again and hopefully try some guided longer exposures to reduce the noise, as well as add some flat and dark frames.



            Andy Mac

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