Trifid Nebula & Messier 21

The Trifid Nebula (catalogued as Messier 20 or M20 and as NGC 6514) is an H II region located in Sagittarius. Its name means 'divided into three lobes'. The object is an unusual combination of an open cluster of stars, an emission nebula (red portion), a reflection nebula (blue portion) and a dark nebula (the apparent 'gaps' within the emission nebula that cause the trifid appearance; these are also designated Barnard 85). Viewed through a small telescope, the Trifid Nebula is a bright and colorful object, and is thus a perennial favorite of amateur astronomers.

Messier 21 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.

This was my second session with guiding, it's a little better having solved some problems. However I think there is still room for improvement. Wind conditions did not help.

Image Data: Trifid Nebula & Messier 21

Lens / Scope: William Optics Megrez 102 S.V. with WO Type II 0.8x FF/FR 
Focal Length: 571.2mm 
F/stop: f/5.6 
Exposure: Stack of 37 300-second exposures (3:05 hours total exposure) 
Mount: Sky-Watcher HEQ5 Pro SynScan GOTO (CdC and EQMOD Control) 
Guiding: Sky-Watcher 80 with QHY5 (PHD Control) 
Camera: Canon 500D (Digital Rebel T1i) Baader Mod (EOS Utility Control) 
Mode: RAW 
ISO: 400 
White Balance: Custom, set on sky background 
In-Camera Noise Reduction: Off 
Filter: Hutech IDAS LPS 
Date: July 08, 2011 
Start Time: 23:45 
Location: Beja, Portugal 
Calibration: 20 Darks, 30 Flats, 30 Dark Flats, 50 Bias. 
Processing: Calibrated, aligned and stacked in DSS. Post-processing in Photoshop. GradientXTerminator. Carboni Tools. Noise Ninja.