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Good evening to you all,
Last night I acquired 30x180s on each RGB so now I have a total of 37x180s each RGB, 60x60s lum from last year, 55x180s lum from this year and some shorter exposures for the core. That means ~5:33h of RGB and 3:45h of lum.
All taken with the ASI1600MMC and the 130PDS newton, horrible gradients when using the light pollution filter. I mean really horrible and uneven gradients. I also have a horizontal line at about 1/4 from the top reflected from somewhere.
The image below was stacked and merged with APP, I also made a synthetic lum from the RGB and included it in the final lum file.
Processing can be improved, for sure, but I have also another thought. Would maybe another 6h of luminance data be worthy on this target? Or should I move to something else, maybe M3 or M92?
Edit: almost 4 more hours of lum.
Edit2: 7 more hours of lum.
Imaging with a 106mm telescope with pulse guiding
I have been posting a few images since I started using the ASI1600MM Cool about a year ago, but they all used my 135mm Samyang lens. In the new year we had a few clear nights and although I wanted to carry on with the mosaic of Barnards loop in Ha7nm, the trees in the hedgerow behind my house became part of the frame – not a good thing. I looked at Star Gazers Lounge for inspiration and many images in January were being posted of the Rosette Nebula, so I slewed over to that, with the 135mm lens and started imaging. The result was ‘ok’ but I felt that the nebula got lost in the stars in such a wide field image. So I decided to put my Astro Tech 106mm EDT APO on the mount and set up for pulse guiding and get up close and personal with the Rosette Nebula. The 106mm scope/guiding wasn’t completely new to me as this was the setup I had used for my initial DSLR imaging. The full run down of the set up is below.
AT106EDT Riccardi 0.75x reducer/flattener
ASI1600 MM cool
Baader LRGB Ha(7nm) filters
I run everything from a Microsoft Surface Pro3 with a single USB3 connection to a USB3 powered hub. The capture software I use is Astro Photography Tool alongside Carte Du Ceil and PHD2. Within APP I also have setup the plate solving and linked that to CdC, I can then use Goto++ to get on target very quickly. I also use the framing mask tool so I can fine tune the aim of the FoV to get repeatable results. This all works quite well, but I always sync the mount and software, so for this sequence of captures I used Zeta Orionis to sync everything up, then I can use Goto++ effectively.
Guiding was ok, I need to understand it a lot more, but I have managed to set it up and get guiding accuracy RA 1.4” RMS and DA 0.72” RMS. What I have to try and improve is that the correction pulses are quite large and occasionally says I have to increase the maximum correction pulse duration. PHD2 reports that I have a polar alignment error of 1.5’ arcmin.
The imaging was carried out over several nights between 9th – 17th February 2018, sky quality was at best variable so the subs were quite a mixed bag. However I captured quite a large number of subs and had to cope with the Rosette transiting the meridian and being obscured by a large bamboo hedge, so I had to meridian flip to keep target in FOV, but kept camera in same position (I don’t have a rotator, or wanted to create a completely different set of flats for flipped images) with the result that the captured subs were a mix of pre and post meridian flipped subs, but stacking software can take care of the inversion.
Baader 1.25” filters
L – 60subs @60s
R – 88 subs @60s
G – 122 subs @60s
B – 84 subs @60s
Ha7nm – 74 subs @90s
Flats - 30
Darks - 30
The ASI1600 was set to -20degC and unity gain. over a period of 4 nights captured a total amount of data for the image of 7.75 hours, however the sharp eyed among you will spot the weakness in this data set – Luminance – I did not capture enough, why, because I was obsessed in getting colour captured , but due to the issues with meridian flip and guiding after meridian flip I ended up with incomplete data sets, FOV offsets and inversions, so I ran my RGB capture plan on two separate capture runs. However, once I got all the RGB, the clouds rolled in and by mid-Feb the moon was too bright for luminance capture and as each day goes by the Rosette headed westwards and into the light pollution bubble from the big logistics warehousing area on edge of town -sigh….
Up to now I have been using Deep Sky Stacker, DSS, however with this Rosette project I found that the DSS stacked images had a lot of noise. I had been reading about Astro Pixel Processor, which Sara Wagner has been using and posted several video tutorials. I decided to use this and have no regrets, yes it has a lot more processing steps and configuration options, but they all make sense and for my subs gave a significantly better final stacked image to take into the next processing stage.
I use RegiStar, I came across this application when reading posts by Olly Penrice, it’s a one trick pony, but it is a brilliant trick and getting all the base stacked images precisely aligned before you start more detailed processing.
I also ‘found’ another very useful piece of software, called Straton, it removes stars from an image and you can then process the nebula without over stretching the stars and losing colour. I played with this quite a bit as another great use is when blending Ha into red channel (and sneaking some into luminance as well) it helps avoid getting holes in stars as the Ha stars are so much smaller than RGB.
There are so many ways to process an astro image it is not my intent to detail workflows here. I use bits and pieces from many sources, including processes from Steve Richard’s Dark Art or Magic Bullet. I have Noels actions, Google NIK plugin, Hasta La Vista Green and Astroflat Pro. My biggest effort goes into reducing the crazy gradients I get on my images due to sports field floodlights, logistics warehouse lighting, and the usual street lighting issues.
NGC2237 Rosette Nebula
So after many, many evenings of processing, reprocessing, trying different blends and masking techniques I leave you with my ‘final’ NGC2237 Rosette Nebula
thanks for reading and getting here, this is the JPEG version with a very light crop to remove stacking artifacts, the PNG was nearly 70Mb so I decided not to post that
Got my 80 Esprit around one week ago and yesterday was the first clear-ish night since. I came to my parents' for Christmas and here the skies are much better. I went to a hill nearby where our galaxy was visible. I had an EQ5 which I didn't polar align very well. I tried to start my RPi3, but it didn't connect to my mobile router so I had to forget about it. I was limited to 15s or 20s subs. The scope is quite heavy, heavier than I expected, it doesn't balance well with a Canon 550D attached. I had to tighten its dovetail towards its end as much as I could and the setup was still camera heavy a bit. Anyways. I left it to cool for maybe half an hour and it didn't reach thermal equilibrium perfectly. Focuser is very good, no slip with the DSLR and tightening it doesn't shift focus. No tilt either.
I bought my scope from FLO and checked by Es.
Here are some pictures taken through it, I only had the camera, no visual stuff.
M45 is 151x15s: https://drive.google.com/open?id=1CbAuNQCGkQPSsPB11UOBkye3Y8EnzNDL
M42 is 14x20s: https://drive.google.com/open?id=1dVgAxK8LQ4jXqPDlv2G0CVjV88UnsU9u
M37 is 10x20s: https://drive.google.com/open?id=1iITFwXffhGvAi4dUbE_qR9_9VQVJszPT
All ISO1600. Darks and bias, no flats.
Today are exactly 2 years since I took my first astrophoto. Quite some progress since then.
Clear skies and happy new year!
90min HII, 72min [NII], and 80min [OIII] in 2 min subs with the 80mm f/4.4 and ASI1600 MMC camera through 3nm Astrodons. Piggy backed on the 130 f/7 mounted on the DDM60 and encoder guided.
Sigma Add stacking in AA5, then gradient removal, alignment and Trichromy with [NII] mapped to Red, HII to Green, and [OIII] to Blue, following the Hubble Palette.
Multiple Histogram Stretches, and a Low Pass filter to get rid of some of the noise. The RGB stack needed a serious crop as the [OIII] subs were at a steep angle to the other data, which is a pity as I can see plenty of outlying detail in the individual stacks.
I'm not taking this particular image any further as the data is too short. I've already got another 2 hours of HII in 5 min subs which I'll stack and add to the existing HII stack. The [OIII] I think I'll bin as it's so badly skewed, I'll try to replace it with 5 min subs properly aligned. The [NII] is OK as it stands, but I'll try to add to it.
When I'll be able to get more data is a moot point, as the weather here has been dire. There *may* be a couple of windows coming up, but I'm not counting on them.
Happy to see the stars again last night, though cirrus clouds were everywhere. With some luck I got some (short) time with lower cloud density and I pointed the scope towards the Orion. 32x30s usable longest subs, 15x10s for the core and I also used 14x20s taken on the 25th to remove the big halos caused by the brighter stars seen through clouds. I could not expose longer, I only had my DSLR and my EQ5 mount, no intervalometer.
The second picture contains some narrowband data I had, which I added in a very small amount to the RGB image. Ha as red and O3 as G and B. This is taken through another lens and it is just an experiment.
The scope seems to perform very well. I can't wait to see what I can get in proper conditions, but it seems that I have to wait a while for this.