NGC 90 - Arp 65

Object: NGC 90: center bottom, galaxy in Andromeda 13.8m, 1.9'x0.8' type SAB(s)c pec and many companions. The extremely long north spiral arm extension reaches two small knots which must be the remnant of a colliding galaxy and/or a starburst region spurred on from the collision. NGC 93 13.6m, 1.4'x0.6' type S to the east. Also distorted from a collision with NGC 90? NGC 83 12.6m 1.5' D type E, middle right side of frame.

Subimages: 20 x 600s (3.3 hrs) SD Mask combined after bias, dark and flat calibration. Input FWHM 2.5" - 3.4", output 3.3" (I rejected 2 frames due to low signal from passing clouds)
Scope: C11XLT with C6.3FR, EFL=1590mm (f/5.7 effective)
Mount: Losmandy G11 with Gemini L4
Camera: ST7EI (1.17"/pixel) set to -25C oriented at 3d39' (N up, E left)
Guiding: SX716 camera on a Taurus Tracker III OAG. Exposure time 4 sec.
Acquisition and Processing: MaxIm DL/CCD v4.5
Imaged on: Nov 21-24, 2006

Processing:
Background flattened manually.
DDP: bgd=1685, mid=1830, filter=Kernel Low Pass More. Click here to see intermediate result.
Created second DDP image in parallel with same settings but no filter. Then used gamma stretch (1.3) in Levels command to equalize the background with the first DDP image.
Clone: Replaced 15 brightest stars with stars from unfiltered DDP image.
Edit Pixels: Fixes small blooms on 3 brightest stars.

For comparison here is the DSS image (POSS2 red) of the same field.