Instrument

12.5" RCOS @  ~f/9 (2897 mm fl) 0.64 arcsec / pixel.  The Zoomify image scale is 0.64 to 3.42 arcsec / pixel.

Mount

Paramount ME

Camera

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

Acquisition Data

8/29/2011 to 9/27/2011 Chino Valley, AZ... with CCDAutoPilot3 & CCDSoft.  AOL guided

Exposure

Lum 510 min (34 x 15 min, bin 1x1 (best of 57)

Ha   540 min (18 x 30 min, bin 1x1

RGB 540 min (12 x 15 min each, bin 2x2)

Software & Processing

CCDSoft, CCDStack, PixInsight, Photoshop CS3, Noel Carboni's actions.

eXcalibrator 3.0 beta (g-r) color balancing, using 31 stars from the SDSS-DR7 database.

CCDBand-Aid version 1.0 to repair STL-11000M vertical bars..

PixFix32 (pre-beta) to repair column defects.

CCDStack to calibrate, register, normalize, data reject,  combine the sub exposures & selective deconvolution.

PixInsight for the LRGB combine, gradient removal, color balance and non-linear stretching.

PhotoShop for adding the Ha data to the red channel, final tweaks and background noise reduction with the Noiseware Pro plug-in.

North is to the right.

M33 is located in the constellation Triangulum, at a distance of about 2.7 million light-years. As the third largest galaxy in our local group, M33 is the most distant object visible to the naked eye. The first historical mention of the galaxy was by the Italian astronomer Giovanni Battista Hodierna before 1654. It was independently discovered by Charles Messier in 1764 and added to his famous catalog as entry number 33, hence the designation of M33.

M33 contains many huge and bright HII star-forming regions; three even have NGC identifications. The largest, NHC 604, is located near the top of the image at about 1:00 o'clock from the galaxy center. NGC 595 is down a bit at 5 o'clock and NGC 588 is at the very bottom, image center. The lower image was taken with an Ha filter and mainly shows just the HII regions.

For more info please see Wikipedia.