Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

NGC 292 mosaic - work in "progress"

  • Please log in to reply
3 replies to this topic

#1 imtl

imtl

    Viking 1

  • *****
  • topic starter
  • Posts: 684
  • Joined: 07 Jun 2016

Posted 03 July 2020 - 08:50 PM

Hi all,

 

I decided to go for a "big" (for me) 3x3 mosaic of the small Magellanic cloud. I tested my run on a clear night with a big moon so I can

work out all the tweaks needed. Which was a good idea! Because there is a lot to learn with mosaics. I don't know how the people with 40+ panels do

it but I salute you all.

 

Anyways, I followed some excellent advice here on CN and I got to the best point I can with the L. When I write best, I mean with getting the best matching panels in matters of seeming and noise level. I do want to emphasize that I only took about 30 minutes data on each panel because I was testing things out so it might be that because of the noise level the differences are enhanced. 

 

The processing was a new thing to learn and it take a huge amount of time to do it. I haven't even started working on the RGB or even to actually process the L besides a simple stretch to post here with my questions.

 

Here is the big image stretched with masked stretch and then some HT and curves.

LumRawMosaic
 
What is bothering me is that if I pixel peep I can still see the seeming and the differences between the panels. 
seem
 
Do you have any advice on what setting to you so I can make this better?
 
When I took the subs I took them all in one night. half hour per panel. I finished that and then I started another cycle of 15 minutes more on each panel. I thought that this way I will average out to the best I can the changing conditions. Seeing was really steady and good the whole night giving me an average RMS guiding of 0.66"/pixel. My image scale is 1.14"/pixel so that pretty good for me.
 
Any thoughts and advice on how to proceed would be very much appreciated.
Thanks
Eyal

 

 


  • elmiko likes this

#2 vnc1218

vnc1218

    Mariner 2

  • -----
  • Posts: 289
  • Joined: 21 Nov 2019

Posted 03 July 2020 - 09:29 PM

How did you combine them in this image?



#3 imtl

imtl

    Viking 1

  • *****
  • topic starter
  • Posts: 684
  • Joined: 07 Jun 2016

Posted 03 July 2020 - 09:59 PM

I created a starfield, aligned each panel, linear fit each to the central panel using the dnalinfit.

Then I used GMM to create the mosaic

#4 imtl

imtl

    Viking 1

  • *****
  • topic starter
  • Posts: 684
  • Joined: 07 Jun 2016

Posted 05 July 2020 - 05:44 AM

Gosh, this was exhausting. Finally I got this thing under control (and learned more PI on the way). I went back to the original panels and realized I was doing the ABE/DBE wrong. I worked carefully building it panel by panel and equalizing the histograms. Once I got that done the seeming of the mosaic was good. You really need to pixel peep to see the seems. Once I acquire more data then the noise STD will be narrower and the differences between the panels will shrink more. I estimated the noise differences and I got to the best point I can with this data. I think it has potential.

 

I've done Lum and blue. Just thinking that now I need to do the same for red and green.... At least I got a workflow going that

seems to give me consistent results.

I need a break from PI smile.gif Too bad its going to be cloudy for another week! That forces me to process images instead of acquiring data!

 

I hope to get a full LRGB image soon.

Edited by imtl, 05 July 2020 - 05:56 AM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics