NGC 3921 (Arp 224) spiral galaxy type (R')SA0/a(s) pec in Ursa Major. In the Arp Atlas, this galaxy is
in the class of “Amorphous Spiral Arms”. To the upper right is NGC 3916, galaxy type SAb: edge-on. At
the far right is PGC 037013, galaxy type Sa, while immediately to the right of NGC 3912 is PGC
2489542, and above and slightly to the left of center is PGC 2491113. Image taken over several nights
from April 20, 2018 to May 14, 2018. Imaged with Starlight Xpress’ SX-825 camera and a Celestron
EdgeHD 9.25 at f10, on a Losmandy G11/Gemini mount. The L subframes were 12 minutes binned 1x1, while
the RGB subframes were 5 minutes binned 1x1 and 4 minutes binned 2x2, resulting in the following total
exposures L:R:G:B (min) = 444 : 70: 70: 70. This image is displayed at 0.57 arc-seconds per pixel.
Captured with Nebulosity, calibrated and sigma combined in Iris with other processing using
PixInsight LE and Photoshop CS. North is up.