NGC 7331 and surrounding galaxies

NGC 7331
All Images Copyright Steve Cannistra

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Magnitude:  9.69
Size: about 10'
Distance: 46 million light years
RA: 22h 37m 06s
Dec: 34 degrees 25' 00"

NGC 7331 is a beautiful spiral galaxy located in the constellation Pegasus.  It was discovered in the mid 1850s by Lord Rosse, who also appreciated the spiral structure of M51.  This field of view shows several galaxies in addition to NGC 7331.

Photographic Details:

Date:  October 12, 2004 (luminance); October 14, 2004 (RGB).
Takahashi Epsilon 250mm aperture, F/3.8 astrograph (850mm focal length) mounted on a Paramount GT1100ME mount, located in an observatory near Mahill, New Mexico.  I accomplished scope/autoguider set up and image acquisition by remote control over the internet from my home in Needham, MA.  A zip file of the raw subexposures was downloaded after completion of the session, ready for processing.  Scope time was rented through Rent-A-Scope.
Camera and autoguider: 
ST-8XE CCD camera (NABG).
Filter:  Custom Scientific Clear, R, G, B filter set.
Exposures:  Luminance: 78' total (12 x 4' plus 6 x 5'), unbinned.  RGB:  3 x 4' each for R, G, and B, unbinned.
Conditions:  Clear skies in New Mexico.  Cloudy in Massachusetts.
Blooms were removed using Ron Wodaski's DeBloomer plug-in for Maxim. 
All images were then dark, bias, and flat frame calibrated.  Alignment done in Registar (images were from different nights, and with different orientation due to meridian flip).  Sigma combined using RC Sigma Reject plug-in for Maxim.  DDP performed in ImagesPlus (IP).  Subsequent processing including levels and curves adjustments in Photoshop CS (16 bit format).

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