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M39 – Open Cluster in Cygnus – ASI294MC Pro

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#1 jgraham

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Posted 13 August 2019 - 08:54 PM

Telescope: Meade N6 at f/5, Baader Mk III MPCC, Orion Atlas EQ-G
Camera: ZWO ASI294MC Pro, 10C; Gain: 200
Filter: Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro II, PHD
Exposure: 60x60sec saved as FITS
Darks: 32x60sec saved as FITS
Flats: 32x10sec, LED tracing tablet covered with 3 layers of muslin
Average Light Pollution: Red zone, poor transparency
Lensed Sky Quality Meter: 18.3 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Nebulosity, Deep Sky Stacker, Photoshop

 

M39 (7-19-2019)-1j.jpg

 

M39 is a large open cluster lying 9 degrees northeast of Deneb. Although sparse, its large size and relatively bright stars makes it is a nice target for binoculars and small telescopes.

 


  • Gregory, eros312, PeteM and 2 others like this

#2 james7ca

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Posted 14 August 2019 - 02:23 AM

Star clusters don't get enough respect in astrophotography and I congratulate you on your fine effort (sharp, with a neutral background, and a mix of star colors). However, I wonder why you used such a high gain and long exposure, since that may have compromised the color saturation in the stars.



#3 jgraham

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Posted 14 August 2019 - 07:56 AM

Using a gain of 200 is my standard setting for the ASI294MC Pro and I chose 60 seconds as a balance between over-exposing the foreground stars and losing the background stars. The transparency was poor with lots of brilliant moonlight, so I was happy with the result. Actually, I was hoping to get better diffraction spikes on the bright stars, but I would have had to push the processing a lot harder to bring them up more than I show here. We only get about 50 clear nights a years (read that as 1 per week, 4 per month) and we rarely get 2 clear nights in a row, so we don't have a lot of time to sweat the details. Grab'n go is the norm. If we get a lucky stretch of clear nights I may go back and revisit a target, both those are generally reserved for special projects (and I don't get a lot of sleep :) ).




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