Quote:
Originally Posted by glend
Grady what gain and offset settings were used, and temperture you were running? Honestly it looks fairly grainy for a ASI1600, suggesting skinny data, but 290x 60sec should be enough. Perhaps its downsize compression for the forum, do you have it in a larger size on Astrobin or Dropbox?
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Sorry glen I don't have Astrobin i have to get round to signing up soon. I was using unity settings, I am trying to keep everything as simple as possible setup wise to see what is achievable, once i have a benchmark i will start playing around with camera settings. As for the graininess of the image, Visually there seems to be limited downsample error from the XISF file to the Jepg mostly i assume because of the heavy crop. I did this stretch very quickly as a demonstration of two things firstly lucky imaging and secondly that this camera can perform from light polluted skies on dim targets using broadband filters. I am not surprised there is a bit of grain in the image really i am impressed it captured this much detail. I ran image states on a random raw image. The difference in average mean ADU from the background to the target is only 240 in a 16 bit image format with the background ADU being 1800 and the target being 2040. Narrow band background ADU i get with this camera is around 8-900 so that show the level of light pollution getting through.
Quote:
Originally Posted by RickS
Impressive for a dim object in less than ideal conditions, Grady. The second image has clearly better detail as you'd expect. You could always do a FHWM biased weighting and use more of the subs to get a balance between detail and SNR.
The ASI1600 has low read noise and decent QE. It doesn't have the power to break the laws of Physics, so shot noise from the target and sky glow is the limiting factor here.
Cheers,
Rick.
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Thanks Rick i an quite pleased with this myself actually given the conditions. I agree with the second image however, i have no idea how to perform biased weighting haha. I suppose some research is in order.
Quote:
Originally Posted by Atmos
Very nice job Grady considering the conditions. You're braver person than I to attempt such a dim target for a light polluted area. I wouldn't touch it unless I'm at a dark site 
Rick is correct, no camera can make it less noisy. In this case we're talking signal (Galaxy) to noise (sky glow) unrelated to camera or equipment. |
Atmos my local BDSM club is shut for the week so i had to do something to keep me sane.
