M 71 - GLOBULAR CLUSTER

SAGITTA

 (ra: 19.53,8/ dec 18:47)

October 2010, Star Party AAAA - Mercedes Observatory Buenos Aires, Argentina

DATA

TYPE: Globular Cluster

Apparent Magnitude: 8.3

Apparent Diameter: 7.2 arc minutes

DISTANCE: 12.700 lights years

IMAGE INFORMATION

SCOPE: Orion Optics UK 150/750 f5 Ultra Grade Mirror with Baader MPCC

CAMERA: QSI 583 WS

GUIDING: Synta 70/400 refractor with Starlight Xpress LodeStar AstroArt 3.0 - Control Interface 3.72 plug in

FILTERS: Astronomik Type II 

SKY CONDITIONS: rural skies - transparency and seeing good

EXPOSURES: LRGB (20,20,20,20) RGB bin 2x2

PROCESSING: Calibration in Images Plus Sigma Media (no darks, flats, bias applied), CCD Sharp, NASA Photoshop Fits Liberator, Photoshop CS2

OBJECT DESCRIPTION AND IMAGE SESSION

Messier 71 is a loose globular cluster in the small constellation of Sagitta. The visible core between 5 to 6 arc minutes has a linear extension of 27 light years. It was first seeing by De Chèseaux a Swiss Mathematician and Astronomer and catalogued by Charles Messier in year 1780. Messier described this globular as a "nebula without stars" and it was first resolved by William Hershel in 1783. (*)

For quite a long time I was looking for M71. Late October is not a good time for the Southern Hemisphere. The session ended 10 to 15 minutes before the clouds started to cover Sagitta area of the sky.

(*) Source Seds