by Anthony Ayiomamitis
PAL 13 in Pegasus is a globular cluster with a weakly concentrated core and as indicated by the image above and its Trumpler classification of "XII". It is characterized with a surface brightness of 17.7 mag/arc-min^2, thus making it one of the dimmest globular clusters within the PAL catalog as well as the Milky Way and which represents a very formidable challenge for observers with large-aperture instruments. Its apparent diameter of approximately 1.8 arc-minutes makes PAL 13 also one of the smallest members within the PAL catalog. PAL 13 lies at an impressive average distance of 82,100 light-years away, thus making it a galactic halo globular cluster within the Milky Way. A recent study found PAL 13 to be 10.5 + 1.0 billion years old! PAL 13 was discovered by American astronomer A.G. Wilson in 1953.
Technical Details:
Date: Oct 9-10, 2009 20:25 - 23:25 UT+3
Location: Athens, Greece (38.2997° N, 23.7430° E)
Equipment: AP 160 f/7.5 StarFire EDF, AP 1200GTO GEM, SBIG ST-10XME, SBIG CFW10, SBIG LRGB + IR-block
Integrations: LRGB @ 60:36:36:36 (3-/6-min subs), 1x1 binning, -15° C
Further details: http://www.perseus.gr/Astro-DSO-Cluster-Palomar-13.htm