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M42+Running Man, 30x90s, Atik 314E with 0.8x reducer

Posted: Sun Jan 06, 2019 7:42 pm
by turfpit
Captured 2019-01-01.
M42-30x90s-Atik314E-0.8x.jpg (102.9 KiB) Viewed 465 times
This was a trial run in preparation for collecting, as weather permits, data sets of the object with LRGB and H-alpha filters plus multiple reduced exposure times to have a look at HDR and try to retrieve the Trapezium.
  • Equipment used - Altair 66ED refractor, Celestron AVX mount, Planostar 0.8x flattener/reducer, Altair 314E CCD camera.
  • Setup - polar align with polar scope, 2 alignment stars + 4 calibration stars, Celestron mount's All Star Polar Align, focus with Bahtinov Mask, unguided. FITS Liberator to inspect test frames prior to imaging run.
  • Software - Sharpcap 3.2 for capture, Siril to calibrate, register, stack, apply histogram transformation. Nebulosity for final post processing - crop, adjust black point, apply contrast (a single click in Curves). The stacking and processing took around 15 minutes.
  • 30x90s, 10 darks, 60 bias, 60 flats.
I also post-processed the stack with GIMP. The use of Nebulosity as a check validates my GIMP actions while I am learning to use the software.

Once again I have noticed that the acquisition of better data results in a much reduced post-processing effort. For the next imaging runs, I think I can squeeze in more of M42 by not having M43 as the centre of the image. Also in post-processing I could apply Nebulosity's Morphological Tightening of Stars.

A satisfying result from a camera which is approximately 10 year old technology and purchased off eBay for £300.


[Atik Camera]
Debayer Preview=Off
Capture Area=1391x1039
Colour Space=MONO16
Output Format=FITS files (*.fits)
Frame Rate Limit=Maximum
Actual Temperature=0
Heat Sink Temperature=0
Timestamp Frames=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.5
#White Point
Display White Point=1

Re: M42+Running Man, 30x90s, Atik 314E with 0.8x reducer

Posted: Sun Jan 06, 2019 7:52 pm
by turfpit
These are example light, dark, bias & flat frames displayed in FITS Liberator.

lights.JPG (25.61 KiB) Viewed 463 times
darks.JPG (33.61 KiB) Viewed 463 times
bias.JPG (35.39 KiB) Viewed 463 times
flats.JPG (35.78 KiB) Viewed 463 times

Re: M42+Running Man, 30x90s, Atik 314E with 0.8x reducer

Posted: Sun Jan 06, 2019 7:59 pm
by turfpit
Here is a log of the capture.

Align red dot finder and telescope on land-based object about 1 mile away. First use eyepiece, then swap in camera ready for mount alignment (2 alignment stars + 4 calibration stars + All Star Polar Align).
initial-scope-setup.JPG (33.93 KiB) Viewed 463 times
Focus with Bahtinov Mask, use Display Histogram Stretch to scrutinise diffraction pattern. Zoom at 175%.
focus.JPG (38.1 KiB) Viewed 463 times
Capture in progress for M42. Note shape of undocked histogram.
capture-in-progress.JPG (35.53 KiB) Viewed 463 times
Capturing flats using homemade EL panel. Exposure adjusted until histogram just left of centre.
flats-capture.JPG (33.05 KiB) Viewed 463 times

Re: M42+Running Man, 30x90s, Atik 314E with 0.8x reducer

Posted: Sun Jan 06, 2019 8:12 pm
by turfpit
I also calibrated, registered & stacked the data set without including the darks. Identical post processing was applied to the no darks stack. An interesting experiment.

No darks.
M42-no-darks.jpg (76.76 KiB) Viewed 462 times

With darks.
M42-with-darks.jpg (76.95 KiB) Viewed 462 times

This is the master dark in FITS Liberator.
master-dark.JPG (79.61 KiB) Viewed 462 times

The master dark stretched in SiriL.
master-dark-stretched.JPG (70.4 KiB) Viewed 462 times