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

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)

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

Click here for the narrow band color mapped 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.

Although taken with narrowband filters, the image is a pretty good representation of RGB colors. Using narrowband filters greatly enhances the detail.

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