Hemisphere:  Northern  ·  Constellation: Canes Venatici (CVn)  ·  Contains:  IC 4263  ·  M 51  ·  NGC 5169  ·  NGC 5194  ·  NGC 5195  ·  NGC 5198  ·  Whirlpool Galaxy
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M51 - cor blighty!, 



    
        

            Tom Gray
M51 - cor blighty!
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M51 - cor blighty!

Getting plate-solving status, please wait...
M51 - cor blighty!, 



    
        

            Tom Gray
M51 - cor blighty!
Powered byPixInsight

M51 - cor blighty!

Technical card

Imaging telescopes or lenses: William Optics Zenithstar II 80 ED

Imaging cameras: Meade DSI 3 Pro

Mounts: Meade LX6 premier with 'smartdrive'

Guiding telescopes or lenses: Meade 8x50mm Finder/Guider

Guiding cameras: Orion Starshoot autoguider

Software: SiliconFields / Ivo Jager StarTools v1.6  ·  Stark Labs Nebulosity v3  ·  PHD2 Guiding V 2.6  ·  Meade Envisage V4.10

Filters: Meade RGB-IR Cut 1.25"  ·  Meade LRGB 1.25"

Accessory: Homemade Dew Controller  ·  Homemade ST4 autoguider


Dates:Feb. 18, 2021Feb. 19, 2021

Frames:
Meade Blue Filter for CCD: 9x60" (9') bin 1x1
Meade Green Filter for CCD: 22x60" (22') bin 1x1
Meade RGB-IR Cut 1.25": 21x300" (1h 45') bin 1x1
Meade Red Filter for CCD: 24x60" (24') bin 1x1

Integration: 2h 40'

Avg. Moon age: 6.69 days

Avg. Moon phase: 42.67%


Basic astrometry details

Astrometry.net job: 4451958

RA center: 13h 30' 3"

DEC center: +47° 2' 27"

Pixel scale: 2.414 arcsec/pixel

Orientation: 89.008 degrees

Field radius: 0.537 degrees


Resolution: 1284x959

Locations: Home 'observatory' (Bortle 5), Derbyshire, United Kingdom

Data source: Backyard

Description

You know how we Brits like to complain about the weather... at last, a few hours of transparency if fairly poor seeing! Not great for imaging, but an opportunity to experiment and hone my skills, and much warmer. I managed a good polar alignment (0-0.2" according to PHD), and lined up on a family favorite, the iconic ‘whirlpool'. I collected 21 x 300s exposures luminance, before racing to get some colour in deteriorating conditions, which is inevitably rather noisy.

Captured in Envisage, pre-processed in Nebulosity and composed in Startools, with standard workflow and use of 'isolate' module to help manage background noise and skyglow. I used interpolation to try and boost the blue channel. Nice to see in wider context with a couple of other obvious galaxies; however, I do think this iconic pair look better at higher scale and resolution - I'll try again in my 2080 SCT on a better night.

Comments

Revisions

  • M51 - cor blighty!, 



    
        

            Tom Gray
    Original
  • M51 - cor blighty!, 



    
        

            Tom Gray
    B
  • M51 - cor blighty!, 



    
        

            Tom Gray
    C
  • Final
    M51 - cor blighty!, 



    
        

            Tom Gray
    E

B

Description: The luminance frames 21 x 300s - aligned and stacked in Nebulosity and processed in Startools

Uploaded: ...

C

Description: This revision has been completely reprocessed using ASTAP - a powerful stacking and astrometric solving tool written by Han Klein, and commended by @rich-sky. I had to do a lot of work renaming FITS header files to specify RGB filters (due to my lazy naming convention), and am still learning the nuances of this powerful free program. This revision is based on an LRGB composite, as I had trouble aligning individual RGB files. The resultant LRGB composite was processed in Startools. I can immediately see an improvement in image quality, colour, detail and depth. For such a short integration and relatively poor RGB data, I am impressed with ASTAP. I would welcome any comments and feedback (especially from ASTAP users)

Uploaded: ...

E

Description: I still wasn't happy with this image which showed alignment errors between the L and RGB channels. Alignment in ASTAP followed by stacking appears to have resolved this and produced a much better image. I think the colour is better and with a saturation boost shows off a little of those blue star forming regions in the whirlpool. I was unable to remove gradients on the right side of the image without severely clipping the data.

Uploaded: ...

Sky plot

Sky plot

Histogram

M51 - cor blighty!, 



    
        

            Tom Gray