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Globular Cluster
Messier 3


M3 globular cluster 2016
Coordinates/Direction : RA: 13h42m, DEC: +28o22'
Object size : 18'
Object magnitude : 6.2
Object : M3
Date : 2016-02-29
Time (UT) : 22:53 to 23:57
Mount : EQ6 controlled by EQMOD
Lens/telescope : TS130, 910mm f7 (682mm, f5.3)
Corrector/Barlow : Riccardi flat field corrector 2.5" x0.75
Filter : none
camera : Canon 6D
Film/CCD : Raw
Exp. time : 28x120 seconds, iso800
Image process tool : Fitswork, Irfanview
Processing : crop, level, no cal dark&bias
Weather : clear
Site : Sweden, Stockholm
Comment : A new attempt to catch the M3 globular cluster. This time wasn't there any moon and a bit darker than normal. I could use 120 seconds exposures which isn't very common from my place. This time I also increased the dithering distance, now it was possible to completely eliminate the hot pixel without dark calibration frames.

If the photo is studied in detail it's possibly to see that it's under sampled, a camera with smaller pixels had been an advantage in this case.

M3 globular cluster 2016

M3 close up

M3 globular cluster 2016
Coordinates/Direction : RA: 13h42m, DEC: +28o22'
Object size : FOV 18'
Object : M3
Date : 2016-02-17
Time (UT) : 22:59 to 00:23
Mount : EQ6 controlled by EQMOD
Lens/telescope : TS130, 910mm f7 (682mm, f5.3)
Corrector/Barlow : Riccardi flat field corrector 2.5" x0.75
Filter : none
camera : Canon 6D
Film/CCD : Raw
Exp. time : 60x60 seconds, iso800
Image process tool : Fitswork, Irfanview
Processing : resize, level, cal dark&bias flat
Weather : clear, moon
Site : Sweden, Stockholm
Comment : My astrosystem setup works better and better.
This photo is taken with the temperature focus compensation activated. The telescope is very sensitive on focus, just a few degrees change in temperature get it off the perfect focus point. One degree Celsius change correspond to 95 step on focus motor.

The AstroTortilla plate solve software that center the object in the frame let me work much faster, get me more time to sub exposures.

The Canon 6D camera has much lower fixed pattern noise and the next thing to do is to work out a procedure that will not require dark calibrations in future. Dithering is one of these tools. Without the dark calibration the random noise will be a bit lower and save me a lot of work and hard disk space.

M3 2015
Object : M3
Date : 2015-03-11
Time (UT) : 21:14 to 22:23
Mount : EQ6 controlled by EQMOD
Lens/telescope : TS130, 910mm f7 (682mm, f5.3)
Corrector/Barlow : Riccardi flat field corrector 2.5" x0.75
Filter : none
camera : Canon 5D
Film/CCD : iso800
Exp. time : 77x30 seconds
Weather : almost clear
Site : Sweden, Stockholm
Comment : One of the first photos with my new TS refractor.
More to know : Wikipedia:
https://en.wikipedia.org/wiki/Messier_3

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