M13 & M27 with Atik 314E

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turfpit
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M13 & M27 with Atik 314E

Post by turfpit » Fri Apr 26, 2019 9:27 pm

Both images captured 25/26 April 2019. Thin high cloud and intermittent lower cloud. Best 80% of frames were stacked.

M27 high res image here https://www.astrobin.com/402775/?nc=user
_M27-100x30s.png
_M27-100x30s.png (257.43 KiB) Viewed 224 times

M13 high res image here https://www.astrobin.com/402754/?nc=user
_M13-120x30s.png
_M13-120x30s.png (179.34 KiB) Viewed 224 times


Equipment: Vixen ED81IIs, Celestron AVX equatorial mount, Altair 1.0x flattener. Mount alignment was 2 alignment stars + 4 calibration stars + All Star Polar Align (ASPA).
Capture: SharpCap 3.2 + FITS Liberator to check test frames prior to imaging run, 30 darks, 50 bias, 50 flats (flats taken using home made flat frame panel), unguided, focus with bahtinov mask.
Processing: calibrated, registered, stacked with Siril 0.9.10. Stack processed in Gimp 2.10

I also captured M51 & M57 in the same session but clouds resulted in too many frames being discarded, leaving nothing worth processing.

M13 and M27 will be targets for some LRGB learning as the weather permits.

Dave

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turfpit
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Re: M13 & M27 with Atik 314E

Post by turfpit » Fri Apr 26, 2019 9:52 pm

Some of the in progress capture screens to hopefully help newcomers with what to expect and things to try.

Focus achieved using a Bahtinov Mask - a £20 item, very cost effective (and simple way) to achieve good focus. Use made of the Display Stretch and Zoom=100% to enhance the display. The star used for M13 was Arcturus and the star used for M27 was Vega - as these stars were near the object to be imaged, therefore same altitude & light pollution conditions.
Arcturus-focus-with-bahtinov-mask.PNG
Arcturus-focus-with-bahtinov-mask.PNG (309.4 KiB) Viewed 221 times


The focused star with Display Histogram Stretch
Arcturus-focused.PNG
Arcturus-focused.PNG (220.58 KiB) Viewed 222 times


M13 capture in progress - note nothing visible on the screen except one star, relying on the shape of the histogram.
M13-capture-in-progress.PNG
M13-capture-in-progress.PNG (182.78 KiB) Viewed 222 times


M13 capture with Display Histogram Stretch
M13-capture-with-display-histogram-stretch.PNG
M13-capture-with-display-histogram-stretch.PNG (302.31 KiB) Viewed 222 times


Flat frame capture - note the logarithmic histogram around 50%. The exposure to achieve this was 50ms.
Flats-capture-in-progress.PNG
Flats-capture-in-progress.PNG (233.11 KiB) Viewed 222 times


The following are a captured light, dark, bias and flat frames displayed in FITS Liberator. The light frame has an ArcSinh(ArcSinh(x)) stretch to ensure the offset is present at the left hand side of the histogram. Note also the dirty optics displayed on the flat frame - essential to remove this from the light frames during the calibration process.


M13-light-frame-histogram-stretched.PNG
M13-light-frame-histogram-stretched.PNG (255.76 KiB) Viewed 222 times
M13-dark-frame.PNG
M13-dark-frame.PNG (273.31 KiB) Viewed 222 times
M13-bias-frame.PNG
M13-bias-frame.PNG (279.32 KiB) Viewed 222 times
M13-flat-frame.PNG
M13-flat-frame.PNG (286.37 KiB) Viewed 222 times

Dave

numchuck
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Re: M13 & M27 with Atik 314E

Post by numchuck » Mon Apr 29, 2019 4:31 pm

Thanks , Dave , for posting all the details . That always helps me .

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turfpit
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Re: M13 & M27 with Atik 314E

Post by turfpit » Mon Apr 29, 2019 6:30 pm

Thanks. It also helps me because it makes me analyse the results and think about what I am doing.

Dave

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