NGC 891


Object: NGC 891: galaxy in Andromeda 10.1m, 11.7'x1.6'


Subimages: 2 x 1200s (0.7 hrs) average combined after bias and dark calibration. FWHM 2.7"-3.5" across the field
Scope: C11XLT with RLS65 reducer, EFL=1981mm (f/7 effective)
Mount: Losmandy G11 with Gemini L4
Camera: ST7EI (0.94"/pixel) set to -20C oriented at 0d33' (N up, E left)
Guiding: SX716 camera on a Taurus Tracker III OAG. Exposure time 2 sec.
Acquisition and Processing: MaxIm DL/CCD v4.5
Imaged on: Sept 29, 2006

Unfortunately I only had time for two frames before clouds rolled in and collimation was not terribly good, good thing this object is fairly bright.

Processing:
Kernel filter: Hot pixel remove with 2% threshold, repeated twice.
Remove bloom: 4 brightest stars
DDP: bgd=1475, mid=3000, filter=Kernel LowPassMore
Clone: Replaced star embedded in galaxy with the same star from a blurred copy of the image. To create the copy I used a gaussian blur (radius=2), and gaussian noise (Amplitude=400).