G1 AKA Mayall II

Andromeda

RA
00 32 46

DEC
+39 34 41

MAG 13.2

Type Globular Cluster?-- UCD (Ultra compact dwarf)?-- Dwarf Elliptical galaxy?

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G1 is one of the brightest globular clusters belonging to M31, the Andromeda galaxy. At 13 .2 Mag it is visible in most amateur telescope. In large scopes at high power stars start to resolve. So what is G 1 ? There are lots of different ideas as to what it is. Here are a few things to think about when you are viewing this most interesting object. 1-- G 1 is three times larger than Omega Centauri our largest globular cluster. 2-- G 1 is about the same distance from the core of M31 as our Large Magellanic Cloud is from ours. 3-- The metallicity of the stars in G 1 is very near the metallicity of stars in the core of Dwarf Elliptical galaxies.

G 1 hubble.jpg

G 1 is the brightest cluster in M31 but according to S. G. Djorgovski of Caltech not the most massive cluster. I will list below three cluster that are near the mass of G 1 or larger. All should be within reach of most scopes.

G 78

RA
00 41 01
DEC
+41 13 47

Mag 14.2

g78.jpg
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G 213

RA
00 43 14
DEC
+41 07 23

Mag 14.6

g213.jpg
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G 280

RA
00 44 29
DEC
+41 21 37

Mag 14.2

g280.jpg


In the image above 3.7 to the South West of G 280 is the cluster G 272 at 14.7 Mag it makes for a interesting field of of view to have two clusters in the same telescope view!!
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I hope you will try some of these "Super Size" clusters next time you are observing and as usual-----

“Give it a go and let us know!”

Good luck and great viewing!