NGC 281 – Pacman Nebula – is an emission nebula in the constellation of Cassiopeia. Right now it is still east of the meridian so I was able to run a 5 hour narrowband session without a meridian flip. The nebula is around 9,200 lys from Earth and almost 50 lys across, and was first charted in 1993 by Edward Barnard. Its common name, Pacman Nebula, comes from its supposed resemblance to the 1980s’ videogame character.
This image is composited from 132 subs of 150 secs each, giving it a total integration time of five and a half hours. I hope to add more to this in terms of data (at least the same amount again) on my next outing.
In terms of my camera, I seem to have ironed out the issues with coma by narrowing down the spacing needed. There is still some slight coma in the outer corners of the subs however, due to rotation during the imaging session, these areas tend to be cropped out anyway.
40 Ha x 150 secs
45 O3 x 150 secs
47 S2 x 150 secs
What is becoming more apparent is that I need to integrate a lot more subs to get the detail I am after. Now we have longer dark periods again at night, I will be experimenting in terms of total integration time rather than number of subs to compensate for the lower SNR created by my shorter exposures.
Anyway, this is where I am with my process – as ever, constructive feedback and comments are welcome.
NGC 281 – Pacman Nebula
More details on Astrobin
NGC 281 – Pacman Nebula
I’m back at work now so my imaging sessions will really be restricted to weekends, weather permitting. The end of August has been pretty poor weather-wise but last night looked good on the forecast and I had 6 hours of dark to play with. Or so I thought.
I wasted so much time trying to get my guiding sorted – no matter what I did, I couldn’t seem to stop the graph oscillating. Turns out I hadn’t enabled guiding – took me an hour to work that out! Then, I had switched out my old finder / guide scope for a dedicated 60mm guide scope but I just couldn’t get it to work properly – I think it isn’t aligned properly and I really can’t do that until the moon is up in a couple of weeks (unless I want to take my kit out in the car and focus on a distant land object, which I don’t!).
Simple lesson learned is to take my time and don’t change out kit that already works well. I went back to my old guiding setup and it guided like a dream all night.
I chose IC 5070 – the Pelican Nebula – as last night’s target and planned for 20×180 of Ha, S2 and O3. Somehow, while transferring the files over this morning I managed to delete 7 of the S2 files!
Anyway, this is an LRGB process of what I did capture. Total integration time is 159 minutes – I’ll probably add more to this on the next session.
20 x 180s Ha
20 x 180s O3
13 x 180s S2
20 darks, 50 flats
Higher resolution on my Astrobin page
Last night was probably my last mid-week imaging session before I go back to work next week. I wanted to return to the Veil Nebula which I imaged earlier on this season; this time to the Eastern Veil of NGC 6995.
I’m still having some coma issues with my focal reducer – I think it might still be spacer related so I am keeping notes and trying different spacers to try and get it sorted. Who knows – maybe I’ll just have to live with it and use judicious framing and cropping.
I had some issues with guiding – I couldn’t get it to settle down, despite several polar realignments throughout the night. In the end, I put it through a meridian shift about 1am then went to bed and letting SGPro finish a run on the O3. I was expecting a folder full of unusable subs this morning but, having run them through PixInsight, I’m ok with them. This is NGC 6995, the Eastern Veil, in a Ha/O3 process. Looks quite patriotic!
Ha (7nm) 20 x 180 sec
O3 (8nm) 40 x 180 sec
25 darks, 25 flats
Higher Resolution on my Astrobin account: