NGC6888_2009-08-14

Nebulae - NGC 6888

R.A.: 20h 12m 07s
Dec.: +38° 21.3'
Mag.: 7.4

The Crescent Nebula (NGC 6888 or Caldwell 27) is an emission nebula in the Cygnus constellation, about 5000 light years away. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray emitting temperatures.

NGC 6888 – Crescent Nebula

Date/time:
15.08.2009 01:05 to 15.08.2009 03:55
16.08.2009 01:15 to 16.08.2009 02:05
Az./Alt. positions:
225° / 75° to 276° / 49°
233° / 73° to 252° / 67°
Ambient conditions: 15°C to 20°C, transparency 4/5, seeing 4/5
Location: Trier, Germany

Equipment:
Optics: TMB 92 SS f/5.5 with TSFlat 2
Mount: CGE
Guiding: selfguiding with ST-4000XCM
Camera: SBIG ST-4000XCM
Filter: IDAS LPS

Acquisition:
Software: CCDSoft V5
FOV, Image scale: 100.9 x 100.9 arcmin, 3.01 arcs/pixel
Sub-exposures: 3h 45min (15 x 15min at –20°),
50 x 10min dark frames,
30 x 0.7s EL flats at –5°C,
50 bias at –5°C for flats calibration

Processing:
Images Plus 3.75. Calibration, Sigma Clip stacking, DDP.
CS3: Curves and level adjustments, Surface blur, Match color.

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Information

Filename: nebulae/crescent_2009-08-14_full.jpg
Filesize: 4048175 Kb
Download limit: unlimited

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