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Here is the Eastern Veil Nebula (NGC 6992/5), part of a large supernova remnant found in the constellation of Cygnus. You are looking at the wispy leftovers of a star 20 times more massive than our sun which exploded some 8000 years ago.
- Sky-Watcher 200PDS telescope
- HEQ5 Pro mount
- ZWO ASI1600MM camera for capture
- ZWO filter wheel, Ha and Oiii filters
- ZWO 120MM camera for autoguiding
- ZWO finder-guider guidescope
- Artesky flats box
- 6th September 2019 from my garden in Glasgow, Scotland.
- 50x120sec with Ha filter, unity gain
- 50x120sec with Oiii filter, unity gain
- 20 flats each filter and 20 darks
- Controlled using Sequence Generator Pro
- Stacked in Deep Sky Stacker
- PixInsight dynamic crop, dynamic background extraction, pixelmath (to produce bicolour HOO image), colour calibration, SCNR, histogram transformation, curved transformation, star mask and star reduction, TGV denoise
- Final denoise with Topaz Denoise and some touch ups in Lightroom.
- More time on the target (less clouds).
- Addition of comma corrector to my imaging train.
- Create mosaic of the wider Veil nebula area.
- Improve PixInsight processing workflow.
After processing the Eastern & Wastern Veils separately a couple of months back, I've finally got round to doing the mosaic that was always the end goal (hence the framing of each panel). I'm not sure why I waited so long to do it, I think deep-down I was secretly dreading it really, as this is my first mosaic so I wasn't really sure how it would go.
So this is just 2 panels, and each one has 5 hrs of Ha (15 x 1200s), with 3 hrs 20 mins of Oiii in one (10 x 1200s) and 3 hrs 40 mins of Oiii (11 x 1200s) in the other. So 17 hrs in total.
APP was used for stacking, gradient reduction, and the mosaic creation. PS used for everything else.
Ha assigned to Red, Oiii to Blue, and Green was synthesized from one of Carboni's actions.
I've tried to push it as far as I dare to, did I over-do it do you think? I've resized it down to 66% to help hide some of the noise, and being a mosaic it's still plenty big. I might even end up bringing it down to 50%, we'll see.
C&C welcome as always. I tend to finish my images very late at night, so I can sometimes fall into the trap of not seeing the image as clearly as I should! So feel free to be as harsh as you like ?
We had a few hours of clear skies here on Saturday night, so I set about getting some O-III for the Western Veil, after I had collected the Ha last month. Thankfully, the moon wasn't around, so even though I didn't get that many subs (only 10) at least they were of good quality.
I actually fell asleep during the capture, and woke up to a 'Sequence Aborted' message in SGP and the sight of PHD2 going mad due to thick clouds. Quickly ran outside and thankfully there was no rain about (phew!). I got 11 subs in total, but the last one was totally unusable due to the clouds. The 10th one was affected too, but still looked useable to me, given that I know from experience that APP's 'Quality' stacking mode would know to give it less of a weighting, so I kept it.
So this is 15 * 1200s of Ha and 10 * 1200s of OIII (8 Hrs 20 mins in total).
Taken with the usual gear: Nikon D5300 (modded); HEQ5-Pro and a SW 80ED.
Calibrated with Flats, Bias, and a Bad Pixel Map. APP used for stacking and gradient reduction. Everything else done in PS (including running Carboni's 'Synthesize Green Channel' action).
After now having processed both the Eastern & Western Veils, I have to say I have found them to be among the hardest targets to process that I've done so far (although it's still early days for me yet, think I'm still under 15 DSO's and counting). I'm not sure if it's down to the sheer number of stars, or the very faint nebulosity that seems to be everywhere, but I've found the background to be especially difficult on these ones. Getting the Ha and OIII nicely balanced before combining probably has something to do with it. I also tend to do gradient reduction (which seems to affect the OIII a lot more than Ha) on the individual stacks before I combine them, so I wonder if I'd be better just leaving it to later in the process? (which I had to do again anyway, as there was still a noticeable red gradient visible later in the workflow).
Something to note, I did go quite heavy on the star reduction. More so than I normally would. I found it wasn't until I upped it significantly, that the nebulosity really started to take centre stage. I like the impact it has made to the image overall, but it made me feel a little dirty at the same time, lol (if that makes any sense).
Also, this isn't actually the finished version just yet. I have a bit more work to do on the background and stars (which need their colour toned down in places - probably shouldn't have ran Carboni's 'Increase Star Colour', in hindsight I don't think it needed it). I was literally falling asleep at the monitor last night while attempting to finish it off, and in the end had to admit defeat. So hopefully I can get around to it later tonight.
Then the next thing will be the big mosaic of both Eastern & Western Veils. I'm both looking forward to, and dreading it, in equal measures ?
As always C&C warmly welcomed!
Pickering’s Triangle (Seimis 3-188)
It is a little early in the season to be imaging this object as it didn’t appear above my local horizon until 00:50 when I started the project earlier this month but with nights getting shorter as we approach the summer solstice, it made sense to make an early start even though it took several nights to capture the data while ducking and diving between the clouds and early morning mist!
Pickering’s Triangle is part of the supernova remnant known as The Veil Nebula in Cygnus. The Veil Nebula itself was discovered by William Herschel in September, 1784 but this faint region was only later discovered photographically in 1904 by Williamina Fleming at the Harvard Observatory. The discovery was made post publication of the New General Catalogue (NGC) so it isn’t included in the catalogue. Although it wouldn’t happen today (I hope!), the custom of the time was to credit the discovery to the lead astronomer, in this case Edward Charles Pickering, the director of the observatory.
Mount: Mesu 200
Telescope: Sky-Watcher Esprit 150
Flattener: Sky-Watcher Esprit specific
Camera: QSI 683 WSG-8
Filter: Astrodon 3nm Ha and 3nm OIII
Subframes: 6 x 1800 sec Ha, 13 x 1800 sec OIII
Integration: 9.5 hours
Control: CCD Commander
Capture: MaxIm DL
Calibration, Stacking and Deconvolution: PixInsight
Post-Processing: PhotoShop PS3
The nebula can be found in the north-west quadrant of the Veil Nebula near NGC 6974 and 79 (see whole Veil Nebula image below). Lying around 1,400 light years away, the beautiful filamentary elements are the expanding shock-wave from the progenitor star that went supernova here somewhere between 5,000 and 10,000 years ago.
Position within the Veil Nebula
Visually, the nebula responds well to the use of an OIII filter as the region is rich in OIII emissions as can be seen in the blue/green filaments in the above images.
Photographically this is a wonderful object that responds well to both LRGB and narrowband imaging and the example shown here was captured using Ha and OIII filters. Although there are sulphur emissions (SII) in this region, this object responds well to my favourite imaging method of 'bi-colour’. This process uses just Ha and OIII filtration wherein the OIII data is mapped to both the ‘Green’ and ‘Blue’ channels and the Ha is mapped to the ‘Red’ channel. The greyscale images below show the individual Ha (left) and OIII (right) images used to produce this image. As you can see from the 'Stats' above, I have a whole load more Ha to collect to complete the image!
The individual Ha and OIII images
I made it out to my dark site on Friday evening, a few high wispy clouds in the sky but for the most part it was quite nice out. The moon was already low and near setting, and I had just received my new Astronomik OIII filter, so I decided to try and find a few objects that have given me fits from the get-go. I started the night taking a long hard look at the double cluster, something I only recently discovered, and then swung the scope around to Albireo, another newer sight for me.
After getting my eyes full of stars, I affixed the filter to my ES 30MM 82° eyepiece. I swung the scope over to the Eastern Veil and WHOA!!!!!! There it was, in all its glory. A little too big to fit the whole thing in the EP at once, I kept swinging the scope back and forth over the length of the nebula, totally blown away with how clear it suddenly was. I had been wanting to see this object from day 1, and have read about people's reactions when they first saw it. I was no different. I don't even know how long I spent swinging the scope back and forth, just taking it all in as if it would disappear at any second. As my first light adrenaline calmed down, I swung the scope down and found the Western Veil as well, another stunning site with 52 Cyg bisecting it and lighting it up so brightly! Just amazing!
I never tired of looking at the veil, but eventually wanted to try to bag a couple more objects. I panned all of the way around to the Rosette Nebula. I found the telltale cluster that lies in the middle of the nebula, and was soon admiring the light ring of smoke surrounding the cluster. With a little time and effort, I was able to tease out enough detail to really see what the Rosette was all about, and once again, I was not disappointed. Next came the Helix Nebula, another object I've tried and failed to find in the past. This night I was successful, though after seeing the prior 2 targets the Helix was more of just a passing find for the checklist.
I scoped out M42 with the OIII filter and was able to make out some details I hadn't previously seen. Since I was already there, I switched to a smaller EP and got some magnification going so I could observe the trapezium, once again managing to see the "e" star but no "f".
I still missed some of the major objects on my list. I have yet to see the Heart or Soul Nebulas and couldn't find them on this night. I have yet to get any substantial views of the North America Nebula. I missed the Witch Head and Cocoon as well.
I took the filters off and surfed around the Universe bagging a few beautiful galaxies, including Stephan's Quintet and the Deerlick Cluster. I scoped out NGC 777 in Triangulum, always a cool object to tease out of the dark skies. I saw NGC 253, the Sculptor Galaxy, for my first time. This is a cool target to which I need to return. A few globulars and open clusters later, and I was getting chilly and ready to call it a night.
All in all I had a great session and managed first light on a few major targets I'd been hoping to see for a long time. As always, there was plenty that I didn't get around to looking for, and more that I missed with an attempt, serving only to heighten my desire to find them on a future night. I'm glad all you folks across the pond are getting some nice views, and it sounds like everyone but me was out looking at the Horsey. Maybe I'll add that my my advanced list of future challenges. Thanks for reading!