NGC 2237

NGC 2237 – Rosette Nebula

 Date/time: 30.01.2009 18:50 to 30.01.2009 23:07
Az./Alt. positions: 116° / 27° to 193° / 44°
Ambient conditions: -5°C, transparency 5/5, seeing 4/5, exceptionally dry air
¼ Moon, Moonset at 22:00
Location: Trier, Germany

Telescope: TMB 92 SS f/5.5 with TSFlat, without dew heater
Mount: CGE, selfguided with ST-4000XCM
Camera: SBIG ST-4000XCM

Software: CCDSoft V5
FOV, Image scale: 98.4 x 100.4 arcmin, 3.01 arcs/pixel
Sub-exposures: 3h 10min (19 x 10min) light frames at –35°C, 45 x 10min dark frames
30 x 1s EL flats at –35°C, 50 bias at –35°C for flats calibration

Calibration, stacking and DDP in Images Plus 3.75,
curves and levels adjustments in CS3, noise reduction with Carbonis Actions,
GradientXterminator, green cast elimination with Pixinsight LE 1.0.

Fantastic conditions for imaging, except for the present ¼ Moon and the street lights
at my observation site. In previous nights I observed that my self-made 32W dew heater was not
enough to avoid frosting of the telescope lense. Some instability of the stars had also been observed.
This time I experimented to insulate the dew cap with a 20mm thick Armaflex, with very good results:
10 hours imaging session without icing and with perfect stable stars.
To eliminate the strong light pollution gradient in the bottom of the image was very tough.

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