Deep Sky

Constellation: Sagittarius
Another gobular cluster discovered by our guy Messier in 1764.  To show you what type of equipment he had, he discribed it as " a nebula contining no star......"   The bright star at the bottom left, is a magnitude star named Kaus Borealis.  This cluster is some 17,900 light-years from earth and astronomers think it is some 12 billion years old.  There are at least 18, RR Lyrae type variable stars in this cluster.  M28 was also the first gobular cluster to be recorded with a millisecond pulsar!  PSR B1821-24,(AKA Speedy) was identified by Lovell Telescope at the Jodrell Bank Observatory in 1986.  Since then, some 11 additional millisecond pulsars have been identified in this cluster using the Green Bank Telescope. According to wkipedia, this is the 3rd largest known population of pulsars in a cluster. Go! M28.....

5 images
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date: 9-15-12