Daily Archives: January 22, 2015

M8, M20, M21, NGC 6559


All four objects on this awesome image are located in Sagittarius:

– The Lagoon Nebula (catalogued as Messier 8 or M8, and as NGC 6523) is a giant interstellar cloud. It is classified as an emission nebula and as a H II region. The Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star-forming nebulae faintly visible to the naked eye from mid-northern latitudes. Seen with binoculars, it appears as a distinct oval cloudlike patch with a definite core. A fragile star cluster appears superimposed on it.

– The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region. It was discovered by Charles Messier on June 5, 1764. Its name means ‘divided into three lobes’. The object is an unusual combination of an open cluster of stars; an emission nebula (the lower, red portion), a reflection nebula (the upper, blue portion) and a dark nebula (the apparent ‘gaps’ within the emission nebula that cause the trifurcated appearance; these are also designated Barnard 85). Viewed through a small telescope, the Trifid Nebula is a bright and peculiar object, and is thus a perennial favorite of amateur astronomers.

– Messier 21 or M21 (also designated NGC 6531) is an open cluster of stars. It was discovered and catalogued by Charles Messier on June 5, 1764. M21 is a relatively young cluster of a mere 4.6 million years of age. It is tightly packed but contains about 57 stars. A few blue giant stars have been identified in the cluster, but Messier 21 is composed mainly of small dim stars. With a magnitude of 6.5, M21 is not visible to the naked eye; however, with the smallest binoculars it can be easily spotted on a dark night.

NGC 6559 is a star forming region located at a distance of about 5000 light-years from Earth, showing both emission (red) and reflection (bluish) regions.

Imaging telescopes or lenses: Pentax 75 SDHF
Mounts: Losmandy G11 Gemini 3
Software: Pleiades Astrophoto, S.L. PixInsinght 1.8 RC7
Filters: Baader Planetarium SII 8nm,  Baader Planetarium Ha 7nm ,  Baader Planetarium OIII 8.5nm 2″
Resolution: 3987×2650
Dates: June 21, 2014,  July 22, 2014,  July 23, 2014
Baader Planetarium Ha 7nm : 18×900″ bin 1×1
Baader Planetarium OIII 8.5nm 2″: 13×900″ bin 2×2
Baader Planetarium SII 8nm: 9×900″ bin 2×2
Integration: 10.0 hours
Avg. Moon age: 24.78 days
Avg. Moon phase: 24.09%
Locations: La Secuita, La Secuita, Spain
Author: Daniel_Trueba