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M51 - Whirlpool Galaxy


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About this observation
John Hughes
Time of observation
29/03/2019 - 21:44
M51 - Whirlpool Galaxy
Observing location
North Essex, UK
William Optics Z61
Celestron AVX Mount
ZWO ASI294MC Pro Cooled
Orion Mini 50mm Guidescope
ZWO ASI120MM-S Guide Camera
Unity Gain 120
Like This Image

This was the first opportunity I had to use the new ZWO ASI294MC Pro Cooled camera. With the Moon only 38% visible and not rising until 3am, I took the opportunity to image a high target until it crossed the Meridian.

Clouds were expected at 2am and with M51 not crossing the Meridian until 00:57am, this gave me a chance to grab a few hours worth of data.

The learning curve continues with obtaining polar alignment and I spend way too much time trying to get this right. Using SharpCap polar align works well after two runs but I also tried drift alignment which didn't go well and just ate into my imaging run.

Calculating exposure time with a dedicated astro camera seems to be a dark art so a trip to the Astrobin website to look at other images of M51 helped. In the end I settled with the following;

Unity Gain 120

Camera temperature -15c

34 light frames @ 300s

25 flat frames, dark flats and dark frames (I had earlier in the day created a dark library for 1, 2, 3, 5 and 10 minute exposures).

Overall I captured 2 hours and 50 minutes of data, by far the longest session I have run so far and I am very impressed with the ASI294MC.

Ideally I would have liked to have used my William Optics Z103 on this small target but I am still getting used to imaging and the WO Z61 is a very forgiving telescope.

Thank you for dropping by.



Jeremy's picture

Lovely result, John. I am especially fond of wide field pics which show galaxies set within their fields

Hughsie's picture

Thank you Jeremy.

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