IC 1276, Globular Cluster
"IC 1276" is the name of a faint globular cluster in the constellation Serpent (Ser), which was first discovered by Lewis Swift in 1889. It was also
found independently by George Abell on plates of the POSS, which is why the cluster also bears the name "Palomar 7".
The apparent magnitude of IC 1276 is given as V= 10.3mag, while its extent is around 8 arcminutes. The globular cluster is not only dimmed in
brightness by the dust masses in front of it, but is also strongly reddened. Nevertheless, the absolute magnitude is still M= -6.7mag, which corresponds
to a luminosity of 41,000 suns. Compared to other globular clusters, however, this is not particularly much, as some of them are 10 times brighter.
The diameter of IC 1276 is given to be around 90 light-years. Because the cluster belongs to concentration class XII, its center is not particularly dense.
The stars in IC 1276 are relatively metal-rich and are around 11 billion years old.
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IC 1276 has a very low surface brightness even in my 20" f/3 telescope, so that with a magnification of 210x a somewhat larger, faint, diffuse cloud
can be seen, whose brightness increases only very slightly towards the center.
The halo appears subtly mottled or grainy at 270x - but individual stars cannot really be made out. Two faint stars can be seen in the halo, but I am
not sure whether these really belong to IC 1276. However, a bright star to the north of the cluster provides a nice contrast.
In total, not the easiest object.
