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Astrodarkness is still almost two months away. This is a reprocess of data I captured in October 2017 with my then new ASI174.
60 x 45 s each of RGB
163 x 30 s L
(3.6 hours total.)
All captured at -20 C, gain 300
ASI174MM-Cool with ZWO LRGB filters. Telescope SW 150-PDS on a SW AZ-EQ6 mount, no guiding
Captured with Ekos/Kstars, processed in PixInsight.
And the old version
So we had a completely clear night last Thursday and, as luck would have it, i was actually off work all week, so i was able to take full advantage. Well, mostly, as you'll soon find out.
As it turned out this was a night that almost went completely awry. The first thing that i messed up was i forgot the external battery that keeps the D5300 powered all night. I only noticed this after driving the 45 min trip back to the family home where i do my imaging. Doh! Luckily though, i dipped into my big bag of astro stuff and found the 2 old camera batteries and charger that i used to use. By my reckoning it was last December when i last used them, so i was amazed to find they still had quite a bit of charge in them! So i was able to charge one while i used the other. Unfortunately though it meant i had to keep going out to the scope every 2-3 hrs to change battery, but tbh i was just relieved that i didn't have to drive home and lose another 90 mins of dark sky time.
The next thing to grumble was the guider. For some bizarre reason, i could not see Polaris in the Fov in Sharpcap. I could barely see anything at all tbh so even though Sharpcap told me it was able to platesolve i was very dubious. And then when i came to do the Sharpcap PA routine, the adjustments were jumping around all over the place. It took me about 25 mins to PA instead of the usual 5, and i really thought the guiding was going to be a nightmare, but what do you know, it turned out to be actually really good. It even dipped below 0.5" at times. Go figure!
Due to the floodlights of the sports facility (which is rather conveniently only about 100 yards away from the house) i was forced to start with Ha subs, then once they were turned off at 10pm, i switched to Oiii, as i knew the moon was coming up around 00:30 so i needed to take advantage of the darkest part of the night. I figured i'd go for about 3 hrs of Oiii, knowing that with the final filter change back to Ha again, i should end up with about 4-5 hrs of Ha in total. Well, after doing the last filter change and going back in to grab a nap for a couple of hrs, when i woke up and checked Team Viewer i noticed that the sequence had unexpectedly ended. Went out and saw that the 7 Ahr LifePo4 battery i use for the mount had died. I also noticed that the lens of the Finder-Guider had completely dewed up. As it turned out, the dew strip for it had failed so i've had to order a new one. I've also ordered a PSU to power the HEQ5-Pro from the mains, so fingers crossed i shouldn't have to worry about mount power over the winter now. All in all this was a bit of a pain of a night, as i normally only shoot 1 filter per night. Sometimes in the longer winter nights i might do 2, but i've never done 3 before. It's a real hassle too, as i need to shoot flats, change filter, re-frame and re-focus. All of which can take upwards of 30 mins. Hmmphh.
So long story short i didn't end up with as much Ha as i wanted for this, which has meant it's been trickier to process than i would have liked. I should probably have just waited and done another night of Ha, but with all the hassle i have to go through to get any imaging done these days (drive, setup, tear down and pack away, drive home, sleep deprivation) i will always just try and use what i've got and move on to the next target. The Mean ADU level was quite low on this one, probably because the target is quite small and only occupies the centre of the frame. I've probably been lucky up to now, by mostly shooting larger targets, so i was disappointed with the low ADU levels, which are scraping the bottom of the barrel for me in terms of getting away from the noise floor. So i upped my exposures a bit, pushing as high as 25 mins, which is the nighest i've ever gone with the HEQ5-Pro. It seemed to still handle it quite well, although it didn't improve the Mean ADU level anywhere near enough.
Full capture details:
3 x 1200s, 2 x 1380s, and 4 x 1500s of Ha
9 x 1200s of Oiii.
11 x 480s of RGB (with an IDAS-D1). Used for the stars and sky background only.
7 Hrs 54 Mins in Total.
All shot with a Nikon D5300, SW 80ED, and an HEQ5-Pro.
The RGB data was shot over a year ago from inner city Belfast (Red Zone) while i was testing out the new Rowan belt mod. It was just a test shot to check the guiding, so the 8 min subs were far, far too long in reality, hence a lot of the medium and bright stars are clipped. But i have to say, the IDAS-D1 together with APP did a nice job of cleaning it right up and making it at least useable (well, by my standards at least!).
So on to processing. I've been playing with this for several nights now, and i just can't look at it anymore! i think this is the best i can manage with the limited data i have. It's been enjoyable and yet frustrating at the same time, lol. As usual, this has been stacked in APP and processed in PS. I used the tone-mapping method of processing, and created a synthesised Sii from a 50/50 blend of the Ha and Oiii. I then combined them in the classic Hubble Palette SHO. Obviously, not having any real Sii means i can never get the full range of tonal variations throughout. I'm also not completely happy with the colours if i'm being honest (especially the blue). That was the part i struggled with the most on this one.
I've also attached below a quick and dirty HaRGB version, which took me all of about 30 mins to process (in total contrast to the SHO version, which i won't say how long it took!).
As always, constructive criticism welcomed with open arms!
Ok time for me to stop rambling on now ?
Edit - Forgot to say, I resized the sSHO version down to 75% of the original (it's not worthy of 100% viewing).
WARNING!!! The following post contains an entirely under-whelming image!
With nothing but clouds here for what has seemed like forever, and no sign of any new data in sight, i decided to turn my attention to some test data i shot back in August of last year. The reason for choosing this, is that i wanted to see how far my processing skills had come along, and i knew this one would be a serious challenge, as i had basically everything working against me.
I shot this near the end of August while testing out the new imaging laptop and rowan belt mod for the HEQ5 Pro (which i had installed the previous winter, but hadn't had a chance to properly test). At the time, we were living very near the City Centre, and only had a tiny back yard, so the only target available was the Pac-Man nebula. This is also before i had the D5300 modified for better Ha response. I did however use my IDAS-D1 filter, which enabled me to shoot 8 min subs. So here's a full rundown:
9 x 8 min subs (only 72 mins in Total)
50 Bias and 30 Flats
Stock Nikon D5300 with an IDAS-D1 filter
Skies were SQM 18.7 (Bortle 6)
AstroPixel Processor was used to stack (with x2 Drizzle), do an initial stretch, and then perform gradient reduction. Everything else was done in Photoshop.
I've shown my previous (hideous!) attempt below as well, which was stacked in DSS and also processed in Photoshop. I should say, i don't think APP played too much of a factor in the improvements, it was mostly just down to better Photoshop skills.
I know i didn't really need to drizzle, i just wanted the nebula to look a bit bigger, so went with the drizzle and then just trimmed the fat off the edges.
Overall i was pleasantly surprised what came out at the end, given this was not much data, done with an unmodified camera in heavy LP.
Anyways, just thought i'd share, to kill the boredom!
I have been struck how different the Pacman looks in RGB compared to NB. To me it looks like a red dust ball in RGB while it looks like an opening into another brighter world in NB (at least in Hubble palette). So here I explored how it may look like in a mix of RGB and NB data.
This is 15 hours of HaOiiiSii data collected by Steve and Lis Milne (aka Gnomus) merged with 3 hours of RGB data collected by me. After a lot fumbling with trying to mix different filters to different channels I ended up making a Hubble image of the NB data and mixed this 50:50 with the RGB image and then tweaked the colours so it resembles the RGB palette. Probably because there is so much data from different sources there was not much noise to deal with. There was more work in dealing with the stars since as usual these were considerably larger in RGB. My processing was done in PS.
Many thanks to the Milnes for allowing me to mess with their data.
The original versions with acquisition data are found here (both are with 5" apo refractors):
Comments most welcome. Is it too bright, too red, wrong red, should there be more dust around (there is a bit more to bring out but I found it slightly distracting, or maybe not...)?
RGB DSLR data from Sunday night. I have noticed this nebula is often processed rather hard, probably to delineate the Pacman shape, so I have tried to do it a bit differently, trying to get out more of the soft red nebulosity around it. I would love to add some Ha data to it one day.
ES 5" apo + Canon 60Da + EQ8. 29 x 6 min. Photoshop
Comments and suggestions most welcome