Instrument

12.5" RCOS @  ~f/9 (2880 mm fl) 0.643 arcsec / pixel.  The Zoomify image scale is 1.28 to 3.11 arcsec / pixel.

Mount

Paramount ME

Camera

SBIG STL-11000 w/ internal filter wheel, AstroDon Gen-I Filters

Acquisition Data

03/01/2009 to 12/26/2009 Chino Valley, AZ... with CCDAutoPilot3 & CCDSoft.

Exposure

SII   600 min (20 x 30 min, bin 2x2)

Ha   450 min (15 x 30 min, bin 2x2)

OIII  450 min (15 x 30 min, bin 2x2)

RGB  225 min (  5 x 15 min each, bin 2x2)

SII:Ha:OIII mapped to R, G & B respectively with an RGB overlay for star colors.

Click here for a synthetic RGB version.
Click here for an Ha filtered b/w version.

Software

• CCDSoft, CCDStack, Photoshop CS w/ the Fits Liberator plugin. Noel Carboni's actions and Russell Croman's GradientXTerminator.

• eXcalibrator for (u-g) color calibration, using 15 stars from the SDSS database.

• PixFix32 (pre-beta) to repair hot/cold pixels and column defects.

• CCDStack to calibrate, register, normalize, data reject, combine the sub exposures & RGB star color combine.

• PhotoShop for Ha:OII:OII color combine &  on-linear stretching.

This false color image was acquired with SII, Ha and OIII filters mapped to the RGB channels respectively. The color channels are stretched to equal levels, clearly showing the presence of sulfur, hydrogen and oxygen. Red indicates the presence sulfur, green hydrogen and blue oxygen.

North is to the left.
Thor's Helmet is about 30 light-years across. The helmet is actually more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble's center sweeps through a surrounding molecular cloud. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. The nebula is located about 15,000 light-years away in the constellation Canis Major.

Source: NASA APOD