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Sculptor Galaxy - Auckland, New Zealand (2020-11-19)

astrophotography beginner imaging
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#1 DarkMain

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Posted 22 November 2020 - 03:12 AM

uJaIHNa.png

Gear:

  • Telescope: Astronz 8" RC
  • Guide scope: Skyrover 60mm guide scope
  • Mount: iOptron CEM25p
  • Camera: unmodified Nikon D7100
  • Guide Camera: QHY 5L-II Colour camera

Software:

  • SiriL 0.99.4
  • Gimp

 

This is my first real attempt at long exposure DSO through a telescope and my first time guiding.

 

  • 26 Light frames @ 180 seconds giving me a total of 78 mins, although I don't know if SiriL used all of them (I used the built in script for stacking and don't know if it culls the worst frames).
  • 20 Bias/offset
  • 10 Dark (I would have liked more, but the camera battery was going flat)
  • 0 Flats (flat battery).

Stacking in SiriL was as simple as setting the working directory then running the OSC stacking script.

Processing was also done in SiriL.

  • Remove Green Noise
  • Background Extraction
  • Colour Calibration
  • Saturation
  • Asinh Transformation

Finally it was finished off in GIMP with some noise reduction, sharpening and a resize.
I know there are some 'issues' with it.
Top right corner has oval shaped stars, which I think means my collimation needs to be improved a little, and the stars are blown out (perhaps a second lot of shorter exposures and a star mask to fix this up?)... A few more darks would have been nice (as well as taking some flats)... But overall, I'm quite happy with how this turned out for a first real attempt.

Any feedback, or comments on how I could improve are more than welcome.
Cheers.

 


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#2 imtl

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Posted 22 November 2020 - 03:42 AM

Hi fellow kiwi

 

Great first shot. This one is starting to be out of season for us as we progress into summer. 

The background is too dark and the galaxy as well. But I think you did real nice on it. More integration time is always good of course.

But first thing is..take flats!



#3 DarkMain

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Posted 22 November 2020 - 04:26 AM

Hi fellow kiwi

 

Great first shot. This one is starting to be out of season for us as we progress into summer. 

The background is too dark and the galaxy as well. But I think you did real nice on it. More integration time is always good of course.

But first thing is..take flats!

How 'bright' should the background be? Its currently about RGB (7,7,7) so there's no clipping.
I find it a little difficult as my two monitors give of very different images so I'm never sure what one is accurate.



#4 imtl

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Posted 22 November 2020 - 04:45 AM

The sky is actually brighter than people think. How did you measure your background to be (7,7,7)? That is out of what? How many bits is the image?

 

It's just an opinion in any case.



#5 DarkMain

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Posted 22 November 2020 - 04:54 AM

That's the RGB value (7 Red, 7 Green, 7 Blue) on the sky in the image I posted. Black being 0,0,0 and white being 255,255,255.

It was converted to 8bit for the web but all the editing was done in 16bit.



#6 imtl

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Posted 22 November 2020 - 05:41 AM

Well I would say it depends but I would put it at least at 10,10,10 for this image. If not more. You're missing out on faint stars and a few faint fuzzies.


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#7 meegja

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Posted 22 November 2020 - 06:55 AM

Well I would say it depends but I would put it at least at 10,10,10 for this image. If not more. You're missing out on faint stars and a few faint fuzzies.

Agreed. My standard is 20/20/20 but with a hardware calibrated monitor. But that's my go-from-point and then alter if if needed when too bright.
Having said that: great capture! waytogo.gif


Edited by meegja, 22 November 2020 - 06:58 AM.


#8 Avgvstvs

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Posted 22 November 2020 - 06:55 AM

Great image, well done




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