MESSIER 25 OPEN GALACTIC STAR CLUSTER

SAGITTARIUS - (ra: 18:31.6 / dec -19:15)

September 2012, -  Star Party Doyle, Buenos Aires - Argentina

DATA

TYPE: Globular Cluster

VISUAL BRIGHTNESS: 4.5

APPARENT DIAMETER: 32 arc minutes

DISTANCE: 2.000 light years

IMAGE INFORMATION

SCOPE: ORION OPTICS UK 6" f5 Newtonian

CAMERA: QSI 583 WS

GUIDING: LodeStar in Synta 70/400 refractor / PHD Guiding

FILTERS: Baader LRGB Set

SKY CONDITIONS: Rural Skies with 40% Crescent Moon at 21 degrees.

EXPOSURES: LRGB (30,30,30,30) for a total exposure time of 2 hours

PROCESSING: Images Plus / Photoshop CS2

OBJECT DESCRIPTION AND IMAGE SESSION

This young open star cluster is located in the direction of the galactic center in a crowded region, near much irregular absorption features on Sagittarius arm. Located about 2,000 light years away from Earth, this little group of stars spans across about 19 light years of space. Caught inside of its influence are four giant stars – two of spectral type M and two of type G. It contains around 86 members that may have began life together some 90 million years.

This galactic star cluster was originally discovered by Philippe Loys de Cheseaux in 1745 and included in Charles Messier’s catalogue in 1764. Oddly enough, it was one of those curious objects that didn’t get catalogued by Sir John Herschel – therefore it never received a NGC number. (*)

One of last chances to grab an object from Sagittarius. It is falling in the west by end of September. The Moon was relatively close at 21 degrees from to M25 but the OOUK Newtonian got very good contrast

(*) Text adapted from fragment of Universetoday