Focal Pointe Observatory
Astrophotography by Bob Franke

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IC 3481, IC 3481A and IC 3483


















Click the image for a wide, 1.16 arcsec/pixel, view. (2100 x 1400 - 1.00 MB)


12.5" RCOS @ ~ f/9 (2880 mm fl) at 0.64 arcsec/pixel. Shown at 1.03 and 1.16 arcsec/pixel.


Paramount ME


SBIG STL-11000 w/ FW8 filter wheel & AstroDon Gen-2 LRGB filters.

Acquisition Data

5/10/2016 to 6/4/2016 Chino Valley, AZ.  with CCD Commander & CCDSoft.  AOL guided



420 min (14 x 30 min) Bin 1x1


360 min (8 x 15 min. each channel) Bin 2x2

eXcalibrator RGB ratios are 1.00, 0.96 & 1.02

Software & Processing Notes

  • CCDSoft, CCDStack, PixInsight, Photoshop CS6.

  • eXcalibrator v5.0 for (g:r) color balancing, using 43 stars from the SDSS-DR9 database.

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

  • CCDStack to calibrate all sub exposures and create the RGB image.

  • PixInsight to register, normalize, data reject, combine the luminance sub exposures, gradient removal, non-linear stretching with HistogramTransformation and to create the LRGB image. PI's HDRMultiscaleTrans was used to enhance galaxy core detail.

  • PhotoShop for the final touch-up.


North is to the left. The galaxies are shown rotated 80 counterclockwise.

From top to bottom, the image shows galaxies IC 3841, IC 3481A and IC 3483. Their respective distances are about 326, 336 and 20 million light-years, toward the constellation Virgo.

A luminous bridge connects IC 3481 and IC 3481A. A larger looping plume extends about two thirds of the way to IC 3483. A photograph, taken with the Palomar 48-inch Schmidt telescope, seems to show the plume extending fully to IC 3483. However, red-shift data indicate that IC 3483 is in the foreground and this is likely a random alignment.

At the upper right-hand corner, of the wide-view, is the galaxy NGC 4503. As a member of the Virgo cluster, it is cataloged as VCC 1412.

The wide-view image also has over 2000 visible galaxies and eleven quasars.  The most distant QSO's z value is 2.87.  This gives a light travel-time of about 11 billion years.