Messier 53 - Globular Cluster in Coma Berenices




Discovered 1775 by Johann Elert Bode.

Globular star cluster Messier 53 (M53, NGC 5024) is one of the more outlying globulars, being about 60,000 light years away from the Galactic center, and almost the same distance (about 58,000 light years) from out Solar system. At this distance, its apparent angular diameter of 13' corresponds to a linear diameter of roughly 220 light years. It is rapidly approaching us. M53 has a bright compact central nucleus, although its stars are not very concentrated toward the center when compared to other globulars, and a gradually decreasing density profile to the outer edges.

Its discoverer Johann Elert Bode, who found it on February 3, 1775, described it as a "rather vivid and round" nebula. Charles Messier, who independently rediscovered and cataloged it two years later, on February 26, 1777, found it "round and conspicuous" and that it resembles M79. William Herschel was the first to resolve it into stars, and found it similar to M10.

As in all globular clusters, the stars of M53 are apparently "metal-poor", which means that they contain only little quantities of elements heavier than helium (actually mainly elements like carbon and oxygen); those of M53 are even below the average globular cluster members in "metallicity". It contains the considerably respectable number of 47 known RR Lyrae variables, some of them were reported to have changed their periods irreversibly with time (Kenneth Glyn-Jones).

In small amateur telescopes, M53 appears as a slightly oval nebulous object with a large, bright center, of rather even surface brightness and evenly fading out to the edges. In somewhat larger telescopes, its outer fringes appear resolved into stars, while the central part is still unresolved and grainy, with one star standing out, in telescopes of about 8-inch aperture. Large instruments of about 12-inch up show it well resolved, with a moderately concenterated nucleus and stars spread out to about 12 arc minutes diameter.


Scope: Planewave 12.5" CDK
Camera: Apogee U16M w Astrodon Generation II RGB Filter set 
Mount: Paramount ME w MKS5000
Guider: ST-402ME
6x5min per channel (LRGB)
Lucknow, Ontario, Canada
Mar 23 2015
Camera temp -25C; No Moon; terrible wind and poor seeing
Images captured w TheSkyX and CCD-Commander
Darks and flats applied in Maxim 
Registration and colour combine in Maxim
Post processing in Photoshop CC 2014