M51 & M13, Vixen 81s+Atik314E, LRGB

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turfpit
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M51 & M13, Vixen 81s+Atik314E, LRGB

Post by turfpit » Tue Mar 24, 2020 12:10 pm

Captured 22/23 March 2020 under Bortle 6 skies.

M51+M13.JPG
M51+M13.JPG (57.02 KiB) Viewed 377 times

  • Celestron AVX mount + Vixen 81s refractor +Vixen 0.67x reducer + Atik314E + Xagyl USB filter wheel + Teleskop LRGB filters
  • Polarscope alignment for NCP, 2 alignment + 4 calibration stars, All Star Polar Align
  • Focus using Bahtinov Mask
  • Capture order for light frames RGBL (imaging East of Meridian)
  • R:30x93s, G:30x36s, B:30x36s, 50 flats, 50 bias, 20 darks all bin 2x2
  • L:75x60s, 50 flats, 50 bias, 30 darks all bin 1x1
  • Astro Pixel Processor, GIMP 2.10 for curves/noise reduction
  • Total Integration 2h 37m per object

Evaluation:
  • My LRGB workflow (personal organisation) is now coming together.
  • RGB colour balancing using different exposures (ratio for RGB is 2.6:1:1) worked as there was no need to employ extreme measures in post-processing software to achieve colour balance. I did have to reduce the red Intensity from 1.0 to 0.8 in APP. I will experiment with an RGB ratio of 2:1:1 in future.
  • M51 is OK but I would like to double the integration time to see the effect.
  • M13, L exposure of 60s is too much as the core is blown. I will try again using 30s and double the L frames.
  • Would like to get to 10h integration for each object (weather permitting)
The uploaded graphic is only 58Kb, the originals have more detail, including NGC 6207 (at top right of M13 graphic).

References:
LRGB Exposures, Brian (@oopfan) https://u235.herokuapp.com/#lrgb-exposure
Color Balance, Brian (@oopfan) https://u235.herokuapp.com/#color-balance
G2V Calibrated Color Imaging, Al Kelly http://www.kellysky.net/


Dave

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oopfan
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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by oopfan » Tue Mar 24, 2020 12:50 pm

Excellent, Dave!

I really like M13 with NGC 6207, the spiral galaxy in the corner.
It's a challenge working with the light pollution filters.

Brian

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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by mAnKiNd » Tue Mar 24, 2020 2:23 pm

Super stuff! Well done Dave :)

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turfpit
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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by turfpit » Tue Mar 24, 2020 2:33 pm

Thanks Brian & Minos.

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turfpit
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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by turfpit » Tue Mar 24, 2020 5:05 pm

This is a crop of the original, denoised using Neat Image trial download https://ni.neatvideo.com/. On my colour calibrated monitor, the core of NGC 5195 (smaller galaxy) has a yellow tinge and the core of NGC 5194 (larger galaxy) is white. This fits in with the M51 Top Picks on Astrobin (although I have a way to go).

_crop_filtered.jpg
_crop_filtered.jpg (71.57 KiB) Viewed 360 times


With the crop loaded into Siril, the statistics maximum value is 63668 which indicates I have not over-exposed.

_max.JPG
_max.JPG (68.59 KiB) Viewed 360 times

I also forgot to mention the wind speed was around 10mph for the M51 capture but it did die down for M13.

Dave

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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by umasscrew39 » Tue Mar 24, 2020 9:16 pm

Very nice, Dave. Great color and nice tracking. I sold my AVX mount but it always tracked great for me. Others have had bad luck with them.

Bruce

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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by turfpit » Tue Mar 24, 2020 9:37 pm

Thanks Bruce.

The scope, reducer, filter wheel + 5 filters + camera weighs about 3.5kg. With this payload I am good for 120s exposures. Much longer and the sky beats me.

Dave

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Re: M51 & M13, Vixen 81s+Atik314E, LRGB

Post by nexusjeep » Sat Mar 28, 2020 9:16 am

Hi Dave,
Nice shots and as always masses of extra information about capture / processing all you are missing is what you had for lunch :D , also I assume at that payload it is a reasonably portable setup. I did some work on mine recently and was pleased to get the scope + accessories down to 14.5kg this will go back up a bit when I put the flattener reducer on the Skywatcher ED72 I am using as the guide scope so I can then guide with the APM 130/780 and put the main camera on the ED72 for some really wide shots so not quite as low as your setup.

Cheers
Nick

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