NGC4725 Spiral Galaxy

Located in the constellation Coma Berenices, NGC4725 is a barred spiral galaxy about 40 million light years away. To many observers, the galaxy apprears to have just one arm, but this image seems to show a short second arm near the end of the main arm. What do you think?

At least three other galaxies complement this image. NGC4747 (upper left) is about 40 to 56 million light years from us. One goal while acquiring and processing this image was to reveal the faint blue extended (and distorted) arms on this galaxy.

NGC4712, is to the right of NGC4725, is much farther – about 207 million light years.

Tiny PGC86434 is at the same level as NGC4747, and ¾ across the image.

Exposure
 • 8¼ hours (49 x 10 minutes) @ -20°C
 • Dusk flats
 • Camera position angle: 0°
Processing  • With PixInsight:
   ☞ Calibrate, star-align, and integrate subframes
   ☞ Background neutralization
   ☞ Process for high-dynamic range
 • Noise reduction with Topaz DeNoise AI
 • Final tweaking in Photoshop CS6
Date and Location  • 2021: April 4 & 5
 • Louisa County, Virginia, USA
Equipment
 • TMB-130SS APO refractor @ f/7 on an A-P 1200 mount
 • ZWO ASI-1600MC Pro color camera
 • Guided with an ST-402 camera on a 60mm f/5 scope
 • Imaging and autoguiding with MaxIm DL 6.20
 • Automated image acquisition with ACP Observatory Control


Updated May 23, 2023