Lorenzo Comolli's Astronomy HomePage

Click on the image for a high res version. MOUSE OVER for H-alpha only. Look also to the H-alpha only hires.

NGC7635, the Bubble nebula, is a giant sphere of gas blowed by the star SAO 20575 (mag. 8.7) in the middle. The diameter is about 5 light years! Here the Bubble is pictured together with many neighbours: the open cluster M52 (top-left), the nebula surrounding the Bubble Sh2-162 or LBN 549, the large nebula in the right half of the image Sh2-161 or LBN 547 filled with dark nebulas (the darker spot on the right is LDN 1228+1229), the bright red nebula NGC 7538 (lower-right), Sh2-159 partially imaged on the lower border.
This image was captured during two nights at the Saint Barthelemy Star Party, the major star party in Italy. This image gained the second place at the photographic competition of the star party.

125% zoom of the Bubble nebula, H-alpha filter.

Technical Data
Optics	TEC 140
Focal Length	1011 mm
Focal Ratio	f/7.2
Exposure Time	Total 8 h 30 min, composed of Ha-RGB 390:40:30:50 min (single exp of 30 min for Ha and 10 min for RGB)
CCD	SBIG STL-11000M @-35°C and @-30°C
Location	Saint Barthelemy football field (AO, Italian Alps) at 1600 m heigth
Date	22-23 September 2017 (2 nights)
Mount	Gemini G-41
Tracking	Lodestar on an 80mm f/5 refractor
Temperature and humidity	T= (+4 to +6) °C, RH=(75 to 100) %
Sky brightness at zenith (with SQM-L)	(21.1 to 21.3) mag/arcsec^2
Notes	Faint veils in the first night when I captured H-alpha; the second night was nearly completely clouded, and I had to fight to get a few RGB exposures. North toward up-right.