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Contains:  Hercules Globular Cluster, M 13, NGC 6205

Image of the day 06/18/2020

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    Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli
    Messier 13 - Great Globular Cluster in Hercules
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    Messier 13 - Great Globular Cluster in Hercules

    Technical card


    Dates:May 3, 2020May 14, 2020May 19, 2020May 25, 2020June 4, 2020

    Frames:
    Astrodon Tru-Balance Gen2 E-Series - B 36mm: 74x120" (gain: 50.00) -20C bin 1x1
    Astrodon Tru-Balance Gen2 E-Series - G 36mm: 65x120" (gain: 50.00) -20C bin 1x1
    Astrodon Tru-Balance Gen2 E-Series - L 36mm: 511x60" (gain: 50.00) -20C bin 1x1
    Astrodon Tru-Balance Gen2 E-Series - R 36mm: 55x120" (gain: 50.00) -20C bin 1x1

    Integration: 15.0 hours

    Darks: ~50

    Flats: ~20

    Flat darks: ~50

    Bias: ~100

    Avg. Moon age: 14.96 days

    Avg. Moon phase: 48.87%

    Bortle Dark-Sky Scale: 5.00


    Astrometry.net job: 3592004

    RA center: 16h 41' 42"

    DEC center: +36° 26' 42"

    Pixel scale: 0.685 arcsec/pixel

    Orientation: 179.118 degrees

    Field radius: 0.510 degrees


    Resolution: 4304x3200

    Locations: Home Observatory, Schenectady, New York, United States

    Data source: Backyard

    Description

    Messier 13 or M13 is the brightest and largest globular cluster visible from the Northern Hemisphere. It was discovered by Edmond Halley in 1714 and cataloged by Charles Messier in 1764. With an apparent magnitude of 5.8, M13 is barely visible to the naked eye from dark skies on clear nights. It appears as a fuzzy spot in low power binoculars and shines like a jewel box in the eyepiece on a larger telescope. It iss a favorite Spring and Summer DSO of mine to observe with the 10in Newtonian telescope.

    M13 is about 145 light-years in diameter and is located at a distance of roughly 25,000 light years from Earth. It contains several hundred thousand stars, which implies an average distance between stars in the Cluster of roughly 1 light-year. However, in the core, stars are much more tightly packed with distances that can be as short as the diameter of the Solar System. Collisions among stars can happen and new stars are formed in the process. These young stars are called "blue stragglers" and form a standalone branch off main sequence in a Hertzsprung-Russell diagram of the stars in the cluster. The stars in the red giant branch of the cluster HR diagram are the oldest and can be used to date the beginning of the cluster formation, almost 12 billion years ago for M13. See also Tolga Gumusayak's APOD image with M13's HR diagram.

    While M13 is a bright DSO and does not require a lot of data, my intent was to resolve faint background galaxies and see how deep I could reach from my Bortle 5 suburban skies.

    The annotated images show fuzzies that can be separated from background unambiguously down to magnitude 22. There are a few galaxies around mag 22.5 that can be kind of resolved but it starts being questionable.

    I used the excellent tutorial by Andre Van der Hoeven to create a custom annotation in Pixinisght.

    References:
    - Wikipedia
    -B. Carroll, D. Ostlie, An Introduction to Modern Astrophysics, 2nd edition, Cambridge U. Press

    Comments

    Author

    lucam_astro
    Luca Marinelli
    License: None (All rights reserved)
    210721
    Like

    Revisions

    • Final
      Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli
      Original
      Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli
      B
      Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli
      C
      Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli
      D

    B

    Description: Annotated image with galaxies from Hyperleda database. The apparent magnitude of the galaxy is reported.

    C

    Description: Inverted luminance image annotated with galaxies from Hyperleda database. The apparent magnitude of the galaxy is reported.

    D

    Description: Crop of the core region of the cluster with the Propeller highlighted.

    Sky plot

    Sky plot

    Histogram

    Messier 13 - Great Globular Cluster in Hercules, 



    
        

            Luca Marinelli