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M13 - jewels in a moonlit sky, 



    
        

            Tom Gray
M13 - jewels in a moonlit sky, 



    
        

            Tom Gray

M13 - jewels in a moonlit sky

Technical card

Imaging telescopes or lenses: Meade 2080 SCT 8" LX5

Imaging cameras: Meade DSI 3 Pro

Mounts: Meade Fork mount w/wedge Meade

Guiding telescopes or lenses: Meade 8x50mm Finder/Guider

Guiding cameras: Orion Starshoot autoguider

Software: SiliconFields / Ivo Jager Startools v1.7  ·  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: Bahtinov Mask  ·  Homemade ST4 autoguider  ·  Finder guider 8x50 Finder Scope


Dates:Feb. 27, 2021

Frames:
Meade Blue Filter for CCD: 14x60" bin 1x1
Meade Green Filter for CCD: 22x60" bin 1x1
Meade RGB-IR Cut 1.25": 54x60" bin 1x1
Meade Red Filter for CCD: 24x60" bin 1x1

Integration: 1.9 hours

Darks: ~20

Flats: ~54

Avg. Moon age: 14.93 days

Avg. Moon phase: 99.97%

Bortle Dark-Sky Scale: 4.00

Mean FWHM: 3.50

Temperature: 4.00


Basic astrometry details

Astrometry.net job: 4262917


Resolution: 1282x997

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

Data source: Backyard

Description

There is definitely a limit to what one can image, and find, under a bright moonlit sky. I’m all for seasonal veg, but couldn’t resist a bright target in the wee hours, more usually associated with a summer feast.

Two consecutive clear nights (or ‘moonlit days’) were a treat, and I spent time getting a good polar alignment (<0.1’ according to PHD) and fine tuning my portable setup. Despite this there is some elongation of stars, mainly, I think due to the poor seeing with FWHM >3” most of the time; reducing guiding to 3s helped to smooth this out.

This LRGB image, just shy of 2 hours, resolves this globular cluster quite well, using 60s exposures, which balanced the bright sky background, and shows hints of the outer stars. On advice of others I have left some sky glow in the background, which remains true to the conditions. Processed using defaults in Startools, I am happy with this, but have included a higher contrast image in revision B (mouse over).

Comments

Revisions

  • Final
    M13 - jewels in a moonlit sky, 



    
        

            Tom Gray
    Original
  • M13 - jewels in a moonlit sky, 



    
        

            Tom Gray
    B

B

Description: A version with more contrast, but some clipping of data, resulting in loss of detail outside the core.

Uploaded: ...

Histogram

M13 - jewels in a moonlit sky, 



    
        

            Tom Gray