SUPERCEDED-NEWER VERSION AVAILABLE---M33 - The Triangulum Galaxy - 2012 version
SUPERCEDED-NEWER VERSION AVAILABLE---M33 - The Triangulum Galaxy - 2012 version
SUPERCEDED-NEWER VERSION AVAILABLE---M33 - The Triangulum Galaxy - 2012 version
M33 is the third largest galaxy in our Local Group of galaxies which includes M31 (the Andromeda Galaxy), and our own Milky Way Galaxy. Visually, the galaxy is quite large - about 70' x 40'. This makes the galaxy about 3 times larger than the full moon. However, unlike the Full Moon, M33 has a very low surface brightness, so it is quite challenging to see as well as to photograph.

The Triangulum Galaxy has many H2 (Hydrogen Gas) regions. In this picture, you can see these H2 regions as the magenta colored areas. Similar to the Orion Nebula and Lagoon Nebula, these regions are areas of star formation.

In this image, North is to the Left. This image is cropped to 97% of the original full frame.

Exposure Details
Lens Celestron C-8 SCT with Celestron focal reducer
Focal Length 1160mm
Focal Ratio f/5.8
Mount Schaefer GEM - 7 1/2 Byers gear
Guiding ONAG On-Axis Guider, Lodestar autoguider, Phd Guiding
Camera Canon 450D modified/ Canon 20Da
Exposure 419 RGB subs of 180 sec at ISO 1600 plus 40 Ha subs of 600 sec at ISO 1600 - 27+ hours of total exp w/focus stacking
Calibration 30 darks, 30 flats, 30 bias
Date 10/19, 20, and 21, 2011; 10/17, 18, and 19, 2012; 11/4/2012
Temperature Various - approximately 55F on most nights
SQM Reading Various - 21.2 - 21.3 (Bortle 4) on most nights
Seeing 4 of 5 on all nights except 10/19/2012 (3/5)
Location Pine Mountain Club, California
Software Used Images Plus 4.0 and 4.5 for camera control, calibration, stacking, digital development, multiresolution sharpening, smoothing and noise reduction. Photoshop CS5 used for levels and curves, selective color, high pass filter, star shrinking, lab color, saturation adjustments, screen mask invert, lens correction, match color, Ha combining, and smart sharpen. Gradient Xterminator for gradient removal. Carboni Tools for additional saturation adjustments, noise reduction, and smoothing. HLVG for additional color correction. Registar 1.0 for stack alignment.
Notes I originally photographed this galaxy in 2011, but the image had some poorly focused edges. This year, I captured additional data to provide a sharper image in the corners, and added some Ha data as well. I used focus stacking to provide a reasonably sharp focus across the field of view, and used my DSLR-LLRGB workflow in processing the image. The new workflow allowed me to saturate the image and bring up some of the faint parts while keeping the chromatic noise at tolerable levels. While I was quite happy with last year's result, I feel that this year's added data and newer processing gives a more detailed view of this impressive galaxy.

If you liked this picture, you might also want to view:

M33 - The Triangulum Galaxy - 2015 version