Capturing The Horsehead Nebula – Barnard 33

Over the last nine months of imaging, I have learned a lot about capturing and processing images. I have also built up a list of targets I want to capture; a list primarily driven by the classic images we’ve all seen before: Andromeda, Orion Nebula and, top of my list, The Horsehead Nebula. For some reason, I had convinced myself that I wouldn’t be able to see the nebula from my backyard due to tree clearance and a neighbour’s house to my south however, I recently noticed it rising on Stellarium when planning another target’s run so I figured I’d give it a go.

I’ve had some issues recently with my QHY163m which has had to go back to China for a repair to the sensor window’s heater and so I’ve been playing around with my modded Canon 100D DSLR instead. The change back down to a DSLR has been notable, especially with the lack of narrowband opportunities. Still, I’m not going to waste any clear nights and so I’ve been re-learning the camera and settings, and imaging a few more obvious targets.

And so to imaging The Horsehead Nebula. I had a clear night last Saturday – almost 12 hours in total so I spent a while gathering more data on Andromeda and having a go at Thor’s Helmet, just to see how it turned out (better than expected but too small for anything other than an experiment). I also planned in 90 minutes on Barnard 33, just to see if I could catch a glimpse of the famous horse’s head back lit by the dramatic red of NGC 2024. I had issues with plate solving and was running out of time when I grabbed a frame that had the nebula in the corner of the frame, and at 90 degrees to where I wanted it. I decided rather than waste any more time, I’d run the sequence and hope I could crop it down.

I ran 20 frames of 240 secs each at ISO 800. These I stacked with 20 darks, and 50 flats and then processed in PixInsight. My processing was minimal as the signal was quite strong – a little noise reduction and then darkening the background with curves, and I was done. I’m really pleased to finally grab my own image of The Horsehead Nebula – it isn’t perfect but I don’t care. I know I can have more time on it as the season progresses.

Full resolution on my Astrobin page: Barnard 33 – The Horsehead Nebula

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M33 Triangulum Galaxy

Autumn has arrived and, with it, the winter galaxies are coming back into night skies. I imaged Andromeda a little earlier this autumn and also had a preliminary go at M33 a couple of weeks ago, but didn’t manage to grab any chrominance subs. I’ve also been having some issues with condensation on my camera which I am still trying to work out. This, combined with the terrible autumnal weather we’ve had, has meant I have had little time to get out and do some imaging. Last weekend, however, I had a good window of weather and so decided to have another go at M33, the Triangulum Galaxy.

M33 is approximately 3 million light years from Earth, in the constellation Triangulum, and is understood to be a satellite galaxy of Andromeda. It’s relatively small size, when compared to M31 Andromeda, and its diffuse nature, makes it harder to image from light polluted skies. This was compounded by the moon being 51% full on the night, although it was already well into western skies as M33 was rising above the treeline to the east of my imaging site.

I imaged using my QHY163m camera at -5c as I suspected that shooting at -20c was contributing to my condensation issues. I also jerry rigged a small 2″ dew heater bought I bought from a brilliant UK supplier, W&W Astro, as well as insulating the camera where the sensor window attaches to the filter wheel. This approach seemed to work as I had no dew issues all night, despite the relative humidity hitting over 90%!

I shot LRGB as follows:

120 x L – 20 secs
60 x RGB – 40 secs each

This gave a total integration time of just under 3 hours total.

The processing in Pixinsight was an arduous task, as it often is with large numbers of subs to work on, and the faint nature of the galaxy, combined with the notable sky fog when stretching, meant a compromise between drawing out the fainter wisps of outer spirals, and keeping the background sky relative flat.

I’m pleased with the overall outcome, although I want to add more data in the near future.

M33 Triangulum Galaxy Crop
M33 Triangulum Galaxy in LRGB

 

And on my Astrobin page

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M31 Andromeda Galaxy

Images of Andromeda Galaxy are what got me interested in astronomy and, more specifically, astroimaging. When I began imaging in earnest, last March, it was the tail-end of galaxy season and I really didn’t have a clue about my equipment. Still, my first DSO was a galaxy – it was a blurred, over-exposed image of Bode’s Galaxy but it was my first image and I was so excited. Suddenly, I began to realise what I was getting in to. These objects are so distant, that we really cannot comprehend the distances. We measure them, not in units of length, but by how long it takes light to travel across them. The thought of capturing photons that have been travelling for millions of years is what keeps me absolutely captivated by astrophotography.

I was too late to image Andromeda last season – and to be honest, I couldn’t even find it when I tried! Since then, I have learned a lot about imaging and the equipment I use. I am passionate about my imaging and processing; I refuse to listen to people who tell me that my skies are too light polluted and that I cannot hope to capture and process deep space images unless I am prepared to travel to dark skies. So it was with anticipation that I waited for Andromeda to reappear on the eastern horizons this month.

I also wanted to get back to using my DSLR as it is a lot easier to point and shoot rather than mess around with LRGB filters. I am back at work and so I want to be able to set up my kit mid-week and leave it running unattended over-night. I recently had my DSLR astro-modded (the IR and UV filters removed). I know that this is more for capturing nebulas however I feel it will also help a little on all DSOs. The work was completed by Andy at Astronomiser and I’m delighted with his work and service. I had the camera back within 10 days and in perfect working order.

I found myself with a clear night on the 21st September – the forecast all week had suggested I might have a couple of hours however, on the morning, the forecast opened up and I had 7 hours of clear skies from 9pm through to light at 4am. I opted to use my Skywatcher ED80 refractor rather than a newtonian as I really wanted to set up, lock focus and then go to bed rather than have to worry about the temperature, collimation and so on.

By 9pm, I was polar aligned thanks to Sharpcap’s polar alignment tool (can’t rate this highly enough) and I just had to wait for Andromeda to rise above the tree line. I got my scopes focused on Vega using my Bahtinov mask, before locking off and programming in my session into BackyardEOS.

I haven’t done much LRGB imaging – all sumer I have been honing my skills on narrowband – and so I wanted some advice on settings etc. A quick chat with Trevor from Astrobackyard.com helped me decide to work on ISO800 and use the histogram to find a good exposure duration. I ended up on ISO 800 for 180 secs as it gave me some separation on the left of the histogram, without moving too far to the right. I ended up running 100 exposures as I had the time to do so, and wanted to grab as much signal as I could for stacking.

The processing took me most of Saturday – I wasted quite a bit of time in Pixinsight but the stack it created had come real issues (I think that using bias frames was a problem) so I re-ran quickly in Deep Sky Stacker to see what happened. This time the stack looked good so I moved it back into PixInsight for processing.

The main problem in processing Andromeda is that the core is so bright, so any stretch results in the core quickly becoming white clipped. I worked using progressive masking to stretch in increments, masking each new stretch to ensure that the core or stars never blew out. This is a technique I have started using and I think it works brilliantly in terms of bringing out detail, even from light polluted skies.

I’m really happy with my result – it is probably my best process to date – but there are some issues that annoy me. There is some horizontal streaking that I have since learned is called ‘walking noise’ and is caused by a lack of suitable dithering. Strangely, I had wondered that the final stack didn’t seem to have much in the way of borders to crop, especially as it was a 5 hour stack. Looks now like either the dither in BYEOS wasn’t enabled or, more likely, it was dithering but not by enough. Another lesson learned. I have plenty of time on Andromeda this year so I will be imaging a lot more galaxies this winter.

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M31 Andromeda Galaxy

Higher resolution on my Astrobin account

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