M 28 - GLOBULAR CLUSTER

SAGITTARIUS

 (ra: 18,24.5 / dec -24:52)

May 2009, Home Backyard in Martínez Buenos Aires, Argentina

DATA

TYPE: Globular Cluster

Apparent Magnitude: 6.9

Apparent Diameter: 11.2 arc minutes

DISTANCE: 18.600 lights years

IMAGE INFORMATION

SCOPE: Celestron C8 SCT working at f6 (roughly)

CAMERA: SXVF H9

GUIDING: William Optics Zenithstar 66 with WO 0.8 x fr/ff

IMAGE ACQUISITION: AstroArt 3.0 - Control Interface 3.72 plug in

FILTERS: Astronomik Type II - Atik Filter Wheel

Magnitude 4 Skies: Conditions - regular 

EXPOSURES: LRGB (20,16,16,16)

PROCESSING: Calibrated in Images Plus Adaptive Add,  CCD Sharp, Photoshop CS2

OBJECT DESCRIPTION AND IMAGE SESSION

Compared to its neighbour M22, M28 appears much smaller. However still a nice target to telescopes also because it is rather easy to find. Just about 1 degree from Lambda Sagittarius (the top bright star of the tea cup) 

M28 presents a diameter of 60 lights years. It is hard to see in the photograph where the globular ends because the dense background star field. This cluster was an authentic discover of Charles Messier catalogued in July 27 1764, but is was William Hershel the first one who described this object as a cloud of stars.

(*) Source Seds