Focal Pointe Observatory
Astrophotography by Bob Franke

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M101 Galaxy














Click the image for a full size uncropped view. (3352 x 2532 1.90 MB) 


Takahashi FSQ-106ED @ f/5.0 (530 mm F.L.) Captured at 2.1 arcsec/pixel.  Shown at 2.1, 4.28 and 9.38 arcsec/pixel.


Losmandy G11 with Gemini L4 v1.0


SBIG STF-8300M Self Guiding Package w/ mono ST-i, using Baader LRGB filters.

Acquisition Data

5/4/2014 to 6/23/2014 Chino Valley, AZ... with CCDSoft & CCD Commander.


Lum 570 min. (38 x 15 min.)   bin 1x1


525 min. (35 x 15 min.)        "

Red 150 min. (10 x 15 min.)  


180 min. (12 x 15 min.)        "


210 min. (14 x 15 min.)        "

Software & Processing Notes

  • CCDSoft, CCDStack, PixInsight and Photoshop CS6.

  • eXcalibrator v4.25 for (g:r) color balancing, using 140 stars from the SDSS-DR9 database.

  • CCDStack to calibrate, register, normalize, data reject, combine the sub exposures and to create the RGB image.

  • PixInsight for gradient removal and initial non-linear stretching.

  • PhotoShop for the LRGB combine, adding Ha data to the red channel and final touch-up.

  • Noiseware 5, a PhotoShop plug-in.


North is to the top.

In the full-size image, galaxies as faint as magnitude 21.7 are easily seen. A count, with the Aladin Sky Atlas, shows at least 7,000 visible background galaxies.


The following is from Wikipedia.
M101 was discovered by Pierre Méchain on March 27, 1781, and he subsequently communicated his discovery to Charles Messier who verified its position and added it to the Messier Catalogue. AT a distance of about 27 million light-years, M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is nearly twice as large.

A remarkable property of this galaxy are its huge and extremely bright HII regions, of which a total of about 3000. HII regions are places in galaxies that contain enormous clouds of high density hydrogen gas contracting under its own gravitational force. Eventually, when the localized hydrogen contracts enough for fusion processes to begin, stars are born.