Iiro's DeepSky Sketches

Name: Messier 21Other name: NGC 6531
RA: 18h 4.2m DEC: -22° 29'
Constellation: SGR
Type: Open cluster
Magnitude: 5.9
Size: 13.0'
Surface brightness: 11
Number of stars: 70
Brightest star: 7.3
Classification: I 3 m
Description: Cl,pRi,lC,st9...12
Notes: In Sgr OB1,36 members to 12th mag
Observer: Iiro Sairanen
Location: Base del Teide (2280m), Tenerife, Spain
Date: 18/19.4.2004 3:50
Instrument: Newton 110/805 mm
Magnification: 107xFilter: -
Field: 28'Seeing: 3
Background sky: 2NE lim mag: 7
Visuality: IHeight: 28°
Weather: +9°C, dry and good
Description: High compressed open cluster in Sagittarius.
Updated: 15.5.2004 13:41