Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_inspirational_skies_winners.thumb.jpg.94f78e21c195e385c5621d89ea0b51b9.jpg

Recommended Posts

Been working on this again, still with old data. Loads of gradients that I can't seem to get rid of. I dumped a lot of [NII] subs that had rubbish stars, elongated and trailed.

TS 80mm f/4.4 six-element astrograph, 3nm Astrodons, ASI1600. I think I ran 5 min subs at max DR. Captured in Maxim DL processed in AstroArt5. Sigma Add stack, multiple gradient removals, ans several Histogram Stretch iterations.

Need more data. I have 2 hours of decent HII, but I want to add new [NII] and [OIII].

5a6e2a8ef3d61_NHOShortN.thumb.jpg.8f756e58d6d031bc66ea5f38a366e0b4.jpg

C&C welcome, and suggestions for further work. The JPEG looks nothing like the FITS I was working on, or how it looks on my monitor from Windows Photo Viewer. Pah!

  • Like 8

Share this post


Link to post
Share on other sites

Nice detail.... I'm glad to be seeing imaged captured by the ASI1600 since I'm in the market for one.... good work.

  • Like 1

Share this post


Link to post
Share on other sites

Thanks guys.

Yes, the 3D effect jumped out at me as I was processing the RGB stack.

The original subs have a much wider FoV, unfortunately they are offset at an angle to each other needing a heavy crop. Hopefully the new data I capture (When I can) will be better aligned.

I still need to get rig of some annoying gradients resulting in an uneven background that multiple gradient removal algorithms failed to cure. Cleaner data should help.

Share this post


Link to post
Share on other sites

I'd be really interested in seeing the single NB channels side by side..... what does the NII look like compared to Ha and OIII for example?

Share this post


Link to post
Share on other sites

Hi Sara

The [NII] is almost as strong as the HII with the [OIII] very weak and noisy by comparison. I'm at work ATM (Naughty!) so I'll see what I can do tonight.

  • Like 1

Share this post


Link to post
Share on other sites
4 minutes ago, DaveS said:

Hi Sara

The [NII] is almost as strong as the HII with the [OIII] very weak and noisy by comparison. I'm at work ATM (Naughty!) so I'll see what I can do tonight.

Thanks! I'd be interested to see not the different strength in the data, but the actual changes in where the data is.....SII is quite interesting on this one.

Share this post


Link to post
Share on other sites

OK

I'll put up the individual stacks, though to get them on here I may have to post JPEGS. I have a Dropbox account (Which I've hardly used) so I'll try to dropbox the original FITS files.

Share this post


Link to post
Share on other sites

I'm not worried about the raw data .... Just a quick stretch jpeg to show the difference would be interesting :) 

Share this post


Link to post
Share on other sites

OK, for Sara @swag72

Firstly, the HII

5a6f70de53d34_HIIstretchforSara.thumb.jpg.8e72df3e0d9c88fb2d603421f28af27c.jpg

Next the [NII]

5a6f70e529f6a_NIIstretchforSara.thumb.jpg.2dbdfa66327960d372f7631cbb04f18f.jpg

Lastly the [OIII]

5a6f70d8533e4_OIIIstretchforSara.thumb.jpg.f767442b4eb26d999ca79924547425f9.jpg

As I intimated, the [OIII] is horribly noisy and all suffer from gradients, the [OIII] worst of all, probably due to imaging in less than brilliant conditions. All are from 5 min subs using the Max DR setting in the ZWO driver.

I will have to recapture good data and dump these dodgy files when I do. I'll probably keep some of the HII data captured most recently.

  • Like 2

Share this post


Link to post
Share on other sites

Many many thanks for this Dave - Most interesting........ :) 

  • Like 1

Share this post


Link to post
Share on other sites

Very interesting more data in the N11 image.

Carole 

  • Like 1

Share this post


Link to post
Share on other sites

You're both very welcome :wink:.

When I first looked at the [NII] data I thought I'd made a mistake and used the HII filter, they're so similar. I think that similarity is what gives the 3D effect.

Share this post


Link to post
Share on other sites

Added more data to the stacks, and dumped some dodgy [OIII] that was very noisy. I also did a lot of pre-processing before stacking. Each set of data was individually stacked and gradient reduced before each group of hydrogen, nitrogen and oxygen data was individually aligned and combined, to give the three components. These were then aligned with each other before each was given a preparatory sequence of histogram stretches. After combining in the NHO palette there was a lot of cropping needed, to get rid of the horribly skewed alignment borders. Another gradient reduction was applied before many small iterations of histogram stretch, with and without curves to give the final result.

5a835f67a6154_AllDatapreprocessed.thumb.jpg.654c03ac1bb81155cd4ac7e03588cdde.jpg

Not entirely sure it was worth the effort, as I think my first version was better.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By moise212
      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?
      Clear skies,
      Alex



      Astrobin: https://www.astrobin.com/341636/
      Edit: almost 4 more hours of lum.
      Edit2: 7 more hours of lum.
    • By bdlbug
      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.

      Capture configuration

      Telescope


      AT106EDT Riccardi 0.75x reducer/flattener


       
      Camera

      ASI1600 MM cool

      Baader LRGB Ha(7nm) filters
      Guiding

      AT72ED
      Lodestar X2

       
      Mount

      Skywatcher
      AZ EQ6-GT


       
      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.

      Image Details

      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.

      Dataset

      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
      Bias -100

       
      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….
      Stacking

      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.

      Registration

      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.

      Misc

      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.

      Photoshop

      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
      Bryan




       
    • By moise212
      Season greetings!
      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!
      Alex



    • By DaveS
      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.
       
    • By moise212
      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.
      Clear skies!
      Alex


×

Important Information

By using this site, you agree to our Terms of Use.