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

andromeda stacked final result in siril

  • Please log in to reply
37 replies to this topic

#1 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 12:13 AM

hello,
I clicked 60 lights for 60 secs, 30 dark frames, 30 flats and 20 bias frames for andromeda at 250 focal length.

Equipment used:

Nikon D750 dslr

tamron 150-600mm telephoto lens

AM5 mount

ASIAIR.

 

I stacked the files in siril and when I saw the final result stretched in histogram, it looked like https://imgur.com/m60nORM. I am not able to see the glimpse of andromeda galaxy.

Earlier when I clicked andromeda with just 20 mins exposure time without a tracker (on a simple tripod) https://imgur.com/4vhAMW3, I was clearly able to see the andromeda in the final result in default histogram in siril.

 

Can anyone help me understand what's going wrong?



#2 D_talley

D_talley

    Fly Me to the Moon

  • *****
  • Posts: 5,248
  • Joined: 07 Jul 2005
  • Loc: Albuquerque, New Mexico

Posted 21 February 2024 - 12:52 AM

Looks to me like you have a lot of light pollution wiping out the image of M31.  Where are you located?  Check your frames, there may be a couple of bad one there. 



#3 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 01:12 AM

Looks to me like you have a lot of light pollution wiping out the image of M31.  Where are you located?  Check your frames, there may be a couple of bad one there. 

I am at bortle 6. Both the images, with and without tracker are taken from same place (my terrace). In the 60 frames I have captured, I can see that the exposure of the lights fit files keep increasing after 30 images (histogram of the image is covering the left and central part).

Even if the light pollution is the culprit, are the lights usable or shall I start fresh in next winter?



#4 The0s

The0s

    Sputnik

  • -----
  • Posts: 26
  • Joined: 18 Sep 2023
  • Loc: Colorado

Posted 21 February 2024 - 02:42 AM

The lights look usable to me. A bit of careful background extraction (maybe even on the sequence itself rather than the final stacked image) should remove the gradients and allow you to see the galaxy more clearly (if there's too many stars, maybe try running it through Starnet++ and then extracting the background). If that doesn't work, I unfortunately think you'll probably have to try again some other time.


  • srvkmr likes this

#5 Cbaxter

Cbaxter

    Apollo

  • *****
  • Posts: 1,290
  • Joined: 29 Mar 2020

Posted 21 February 2024 - 03:05 AM

It looks like something went wrong in the stacking process. Try stacking just the light frames without any calibration frames (darks, flats, etc). If you get a good but uncalibrated final stacked image, then you know to investigate your calibration frames. Especially the flats.

Edited by Cbaxter, 21 February 2024 - 03:06 AM.

  • srvkmr and Domdron like this

#6 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 06:06 AM

It looks like something went wrong in the stacking process. Try stacking just the light frames without any calibration frames (darks, flats, etc). If you get a good but uncalibrated final stacked image, then you know to investigate your calibration frames. Especially the flats.

I tried this. The galaxy was still not visible in the default histogram stretch and the final image had a greenish tint.



#7 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 06:27 AM

The lights look usable to me. A bit of careful background extraction (maybe even on the sequence itself rather than the final stacked image) should remove the gradients and allow you to see the galaxy more clearly (if there's too many stars, maybe try running it through Starnet++ and then extracting the background). If that doesn't work, I unfortunately think you'll probably have to try again some other time.

Shall I try to reduce the exposure of the light frames, which has their histogram stretching till center and then try stacking?



#8 marvyyk

marvyyk

    Surveyor 1

  • -----
  • Posts: 1,695
  • Joined: 13 Sep 2020
  • Loc: St-Jean-sur-Richelieu, Quebec

Posted 21 February 2024 - 06:44 AM

I'm surprise with the gradient for a Bortle 6. I'm in a B9, and it did not cover that much of the image... Did you take M31 high in the sky?? 



#9 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 12:17 PM

I'm surprise with the gradient for a Bortle 6. I'm in a B9, and it did not cover that much of the image... Did you take M31 high in the sky?? 

No. I cannot in February. After 19:00 hours, I hardly have one hour left to shoot before it hides behind nearby building.



#10 unimatrix0

unimatrix0

    Fly Me to the Moon

  • *****
  • Posts: 6,459
  • Joined: 03 Jan 2021

Posted 21 February 2024 - 01:55 PM

Try stacking them without the flats and biases to close out the possibility that your flats are no good. Just stack the lights. 


  • Cbaxter likes this

#11 vidrazor

vidrazor

    Fly Me to the Moon

  • *****
  • Posts: 5,468
  • Joined: 31 Oct 2017
  • Loc: North Bergen, NJ

Posted 21 February 2024 - 02:54 PM

What does the histogram of your subs look like? If they're past the mid-point, you've flush out the dimmer galaxy data out with light pollution. What ISO did you shoot at? Now Bortle 6 isn't bad, but if you're low in the sky you're gonna get slammed with local sky glow.

 

Can you post your stack online for download?


Edited by vidrazor, 21 February 2024 - 02:55 PM.

  • srvkmr likes this

#12 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 21 February 2024 - 09:56 PM

What does the histogram of your subs look like? If they're past the mid-point, you've flush out the dimmer galaxy data out with light pollution. What ISO did you shoot at? Now Bortle 6 isn't bad, but if you're low in the sky you're gonna get slammed with local sky glow.

 

Can you post your stack online for download?

https://drive.google...iew?usp=sharing

 

here is the final stacked file. In the final image data, the histogram doesn't cross the mid point.

ISO 800.

The subject wasn't low in the sky because I have a house in front of my house and before the subject goes down the horizon, my camera will capture pictures of the house.



#13 vidrazor

vidrazor

    Fly Me to the Moon

  • *****
  • Posts: 5,468
  • Joined: 31 Oct 2017
  • Loc: North Bergen, NJ

Posted 22 February 2024 - 01:49 AM

here is the final stacked file. In the final image data, the histogram doesn't cross the mid point.

ISO 800.

The subject wasn't low in the sky because I have a house in front of my house and before the subject goes down the horizon, my camera will capture pictures of the house.

The best I can deduct is that some local light source screwed your session up. Is there a stadium nearby? Was the moon up? Neighbor's light that wasn't turned on before?

I ran your stack through GraXpert AI, and got the results you see below. Curious about the optical anomaly, although it may not show up under normal conditions.
 

Another possibility is something's off with your calibration frames for some reason. Perhaps a lens can wasn't properly on. You should open up and autostretch your darks and bias FITS stacks that Siril makes. Also, try just stacking your lights using the OSC_Preprocessing_WithoutDBF.ssf stacking script, and see what you get. If by chance you don't have that script, you can find it and others, here.

 

Attached Thumbnails

  • blown m31.jpg

  • srvkmr likes this

#14 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 22 February 2024 - 07:11 AM

The best I can deduct is that some local light source screwed your session up. Is there a stadium nearby? Was the moon up? Neighbor's light that wasn't turned on before?

I ran your stack through GraXpert AI, and got the results you see below. Curious about the optical anomaly, although it may not show up under normal conditions.
 

Another possibility is something's off with your calibration frames for some reason. Perhaps a lens can wasn't properly on. You should open up and autostretch your darks and bias FITS stacks that Siril makes. Also, try just stacking your lights using the OSC_Preprocessing_WithoutDBF.ssf stacking script, and see what you get. If by chance you don't have that script, you can find it and others, here.

Thank you for putting your valuable time in this project.

There is a big light flood light source. But it didn't screw up my Orion nebula project.

Yes there was half moon but at some distance from Andromeda.

I tried stacking the file without calibration frames but I didn't see any details. Also It has a green tint overall.

I tried to stack flats of FL 600mm, which I took for orion nebula but it didn't work either.

I will try to take calibration frames again.

 

Here is the attached image with only lights stacked.

Attached Thumbnails

  • 5.jpg


#15 vidrazor

vidrazor

    Fly Me to the Moon

  • *****
  • Posts: 5,468
  • Joined: 31 Oct 2017
  • Loc: North Bergen, NJ

Posted 22 February 2024 - 12:01 PM

Thank you for putting your valuable time in this project.

There is a big light flood light source. But it didn't screw up my Orion nebula project.

Yes there was half moon but at some distance from Andromeda.

I tried stacking the file without calibration frames but I didn't see any details. Also It has a green tint overall.

I tried to stack flats of FL 600mm, which I took for orion nebula but it didn't work either.

I will try to take calibration frames again.

Here is the attached image with only lights stacked.

The moon will create quite a bit of sky glow.

 

Orion and Andromeda are on opposite parts of the sky, as you can see below. This could cause you to be affected by a local light source shooting M31 that wouldn't affect you while shooting M42.

 

You didn't have to stack them the calibration frames, Siril already has done that, you can find them in the process folder when you stacked the lights/darks/flats/biases. That was the file I was referring to.
 

Attached Thumbnails

  • targets.jpg

  • srvkmr likes this

#16 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 22 February 2024 - 11:13 PM

The moon will create quite a bit of sky glow.

 

Orion and Andromeda are on opposite parts of the sky, as you can see below. This could cause you to be affected by a local light source shooting M31 that wouldn't affect you while shooting M42.

 

You didn't have to stack them the calibration frames, Siril already has done that, you can find them in the process folder when you stacked the lights/darks/flats/biases. That was the file I was referring to.
 

I think this winter I will not get anymore chances to shoot andromeda as its already close to horizon by dark. I will try next winter. Thank you all for the help and valuable time.



#17 sharkmelley

sharkmelley

    Fly Me to the Moon

  • *****
  • Posts: 7,373
  • Joined: 19 Feb 2013
  • Loc: UK

Posted 23 February 2024 - 01:07 AM

Can you upload a raw flat, a raw light and a raw bias to a file-sharing site.  It should then be possible to see where the problem originates.

 

Mark


  • srvkmr likes this

#18 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 24 February 2024 - 03:32 AM

Can you upload a raw flat, a raw light and a raw bias to a file-sharing site.  It should then be possible to see where the problem originates.

 

Mark

https://drive.google...iew?usp=sharing,

https://drive.google...iew?usp=sharing,

https://drive.google...iew?usp=sharing,

https://drive.google...iew?usp=sharing,

https://drive.google...iew?usp=sharing

 

Here are the links for 1 flat, bias & dark frames & 2 lights, one of the first & other of the last.



#19 sharkmelley

sharkmelley

    Fly Me to the Moon

  • *****
  • Posts: 7,373
  • Joined: 19 Feb 2013
  • Loc: UK

Posted 24 February 2024 - 10:49 AM

Surprisingly, it would appear that the major contributor to the gradient in your stacked image is the flats.  The flats have a strong top-to-bottom gradient which is then imposed on your calibrated files.


  • srvkmr likes this

#20 vidrazor

vidrazor

    Fly Me to the Moon

  • *****
  • Posts: 5,468
  • Joined: 31 Oct 2017
  • Loc: North Bergen, NJ

Posted 24 February 2024 - 08:27 PM

Here are the links for 1 flat, bias & dark frames & 2 lights, one of the first & other of the last.

Your lights are way too hot for your Bortle. You need to be around 1/4-1/3 from the left, as seen on the back of your Nikon. Also, why are your files monochrome?

Attached Thumbnails

  • HOT 1.jpg
  • HOT 2.jpg

Edited by vidrazor, 24 February 2024 - 08:37 PM.

  • srvkmr likes this

#21 sharkmelley

sharkmelley

    Fly Me to the Moon

  • *****
  • Posts: 7,373
  • Joined: 19 Feb 2013
  • Loc: UK

Posted 25 February 2024 - 04:46 AM

Also, why are your files monochrome?

The files are monochrome because DSLR raw files are always monochrome before debayering.


  • srvkmr likes this

#22 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 25 February 2024 - 06:06 AM

Surprisingly, it would appear that the major contributor to the gradient in your stacked image is the flats.  The flats have a strong top-to-bottom gradient which is then imposed on your calibrated files.

So shall I try to retake the flats? Just for info I tried to stack with flats at 600 FL, which I took for orion nebula but the result wasn't usable.



#23 srvkmr

srvkmr

    Explorer 1

  • -----
  • topic starter
  • Posts: 86
  • Joined: 27 Oct 2022

Posted 25 February 2024 - 06:08 AM

Your lights are way too hot for your Bortle. You need to be around 1/4-1/3 from the left, as seen on the back of your Nikon. Also, why are your files monochrome?

Yes DSLR fits are monochrome before I poke them.

So shall I use ISO 400 or increase my aperture or lower down the shutter speed of single shot next time?



#24 vidrazor

vidrazor

    Fly Me to the Moon

  • *****
  • Posts: 5,468
  • Joined: 31 Oct 2017
  • Loc: North Bergen, NJ

Posted 25 February 2024 - 11:36 AM

So shall I use ISO 400 or increase my aperture or lower down the shutter speed of single shot next time?

Shutter or aperture. A smaller aperture should give you some extra sharpness.
 


  • srvkmr likes this

#25 Catchlight

Catchlight

    Sputnik

  • -----
  • Posts: 30
  • Joined: 26 Jan 2023

Posted 25 February 2024 - 12:16 PM

Just for reference, I did a Bortle 6 full moon session of Andromeda last month with the following data: (I would have liked to have more light frames, but still turned out well considering.) In any case 60 secs at f/5.6 at iso 800 should correspond to my 30 secs at f/4

https://www.cloudyni...640_1712018.jpg
Equipment
Lens Canon EF 600mm f/4L IS III USM
Camera Sony A7RIII
Mounts Sky-Watcher Star Adventurer GTi
Acquisition details
Dates: Jan. 25, 2024
Frames: 104×30″(52′) ISO800 f/4
Integration: 52′
Darks:45
Flats:30
Bias:40
Avg. Moon age:14.54 days
Avg. Moon phase:99.94%
Bortle Dark-Sky Scale: 6.00
Location: Lund, Sweden, Skåne län, Sweden
Data source: Backyard


Edited by Catchlight, 25 February 2024 - 12:35 PM.

  • srvkmr likes this


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