Focal Pointe Observatory
Astrophotography by Bob Franke

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NGC 4725 & 4747 Galaxies


Click the image for a full size view.


Roll the cursor in and out of the above image, to see galaxies identified from the NED database. In this color inverted, partial view, faint galaxies at magnitude 22.5 are easily visible... with the faintest visible found at 23.7. Within the entire field of view, there are about 2,050 galaxies at magnitude 22.5 or brighter. 



12.5" RCOS @  ~f/9 (2880 mm fl) at 1.28 arcsec / pixel.


Paramount ME


SBIG STL-11000 w/ internal filter wheel, AstroDon Gen-1 Filters

Acquisition Data

2/13/2010 to 2/23/2010 Chino Valley, AZ... with CCDAutoPilot3 & CCDSoft.


Lum  330 min. (22 x 15 min. bin 2x2)

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

Software & Processing Notes

  • CCDSoft, CCDStack, Photoshop CS6, PixInsight and Noel Carboni's actions.

  • eXcalibrator v4.1 for (g:r) color balancing, using 16 stars from the SDSS-DR9 database.

  • CCDBand-Aid to repair Kodak KAI-11000M vertical bars.

  • CCDStack to calibrate, register, normalize, data reject, combine the sub exposures, create the RGB image and selective luminance Maximum Entropy deconvolution.

  • PixInsight for gradient removal, initial non-linear stretching and selective use of HDRMultiscaleTrans to enhance the detail in the center of the galaxies.

  • PhotoShop for the LRGB combine & final touch-up.

  • Noiseware 5, a PhotoShop plug-in.


North is to the top.

This beautiful trio of galaxies is in the area of the constellation Coma Berenices. NGC 4725 (center) and NGC 4747 (upper left) are neighbors at a distance of 45 to 57 million and 40 to 56 million light-yrs respectively. Galaxy NGC 4712, at the lower right, is in the background... about 207 million light-years away.

Tidal interaction with supergiant spiral NGC 4725, is the generally accepted cause for the severe distortion of the smaller NGC 4747 galaxy. This interaction has given NGC 4747 three tidal tails, two large at the upper left and a smaller one at the opposite end of the galaxy. The direction of these three plums trace directly towards NGC 4725.

NGC 4725 has its own peculiarities. While most spiral galaxies have two or more arms, NGC 4725 seems to have only one.