Sunday, October 26, 2008

Scope & Camera Finally Meet!

On the night of the Lunar imaging that I posted previously, I also finally put my 20D on the end of my telescope at prime focus. I was happy I knew how the camera operated, and I had been playing with using my laptop to control the camera via a custom cable release controlled by the parallel port - which basically meant the laptop held the bulb down and did the exposure counting rather than me and my thumb :) I was ready for the next step in my imaging journey.

I needed something bright and easy to start with, so the first target was the Great Globular Cluster in Hercules - M13. It's one the brightest globular clusters in the Northern Hemisphere and is just visible to the naked eye on a
good night. Although easily seem with 10x50 binoculars, the stars only really start to resolve out of the blob when you turn a telescope towards it. With hundreds of thousands of stars present, the more aperture you have to hand the more stars you can resolve. Visually, some people claim there are patterns inside the cluster - a propeller is quite often cited - though I do wonder if it's just a case of the classic "averted imagination" (which is our local societies take on the averted vision technique that some of the experienced observers tend to use when seeing things nobody else can!). I also have horrendous memories at university being made to count the number of stars in the cluster using a magnifying glass .... thank god for the invention of computers to do such tedious things for you! Anyway, on with the first image!


This image is a crop from a larger frame, and you can also see a small friend to the north east of the cluster called NGC 6207 - a 12th magnitude edge on galaxy. This is just a line of sight effect mind and the two are not related in any other way than their apparent position in the sky.

The image is a summation of 13 two and half minute exposures, stacked in Deep Sky Stacker, and given the obligatory PixInsight and Photoshop treatment. I'm finding now that I need to do around 3 attempts before I get one that I find satisfactory - and almost always the first one is never the best.

I felt I was on a roll by this time in the evenings preceedings. M13, a lunar mosaic, what more could I want .... Well, I really wanted to try to capture the North American Nebula, but knew my camera was not the most sensitive in the Hydrogen Alpha light that this nebula throws out in spades. This didn't stop me from wanting to have a go though! Unfortunately, I quickly realised that ther was no way I could spot the nebula in either the finder, 10x50's, or telescope itself (as mentioned in some of my previous posts) so I needed to have a leap of faith. I had a rough idea from a star chart I had to hand, but with only the finder to line up, it was a serious case of "point and hope"

Well, lady luck was obviously on my side again, as extremely faintly in the background of the image data was a nebula bursting to get out. It needed some heavy proce
ssing, but luckily it seemed to take it well, and this was the result.

I was a very happy man when I teased this data out of the set! It's a stack of 12 two and a half minute lights, and you can see quite a bit of detail in there when you start to look. Yes, a little noisy, but that's to be expected with the ISO, processing aggressiveness, and low frame count, but definitely a keeper :)

I performed the normal DSS stacking (with flats, darks, and bias frames), a hefty session in PixInsight, and a fair bit of tweaking, layering, and exposure balancing in Photoshop to get the best out of the data.

I'm rather proud of the result to be honest! The framing could not have been better (there's no cropping here). All in all the most successful imaging night to date! I suspect next time I won't be as lucky :(

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