NGC 7331 - Galaxy and Friends


Known as the Deer Lick Group, this field is dominated by NGC 7331.  It is in the constellation Pegasus (the Winged Horse), and has a magnitude of 9.5.  At 45 million light years away, it has a size of 10.0 x 3.0 arc-minutes. Besides the main galaxy, there are five other galaxies in the group.

The above image was taken over two nights: the luminance on Sept 6, 2002 and the color on Sept 27.  It was taken from the Mistletoe observatory with the 12" LX200, ST-8E, and AO7 at f/6.3.  The luminance alone is below with the full exposure details below that.


Exposure Count Binning
Luminance 25 min 5 x 5 min 2x2
Red 20 min 2 x 10 min 2x2
Green 20 min 2 x 10 min 2x2
Blue 20 min 2 x 10 min 2x2

Previous try (LRGB) on Nov 18 2000:

Taken  from the Mistletoe site outside of Monmouth Oregon with the 12" LX200 at f/6.3 and SBIG ST-8E.  Self-guided.

This image is an LRGB composite of six 10 minute luminance, one 10 minute red, one 10 minute green, and two 10 minute blue frames.  L is unbinned, and RBG frames are binned 2x2. A color balance of 1.15 : 1.00 : 2.05 was modified by having an altitude of 64, giving a final color balance of 1.14 : 1.00 : 2.07.

At the 1997 Oregon Star Party this object showed up on the charts near where I was pointed at the time. I didn't know what it was, but it seemed worth a shot.  This was my first experience with NGC 7331.

A 3 minute exposure taken with the 416 at f/3.3. The dark frame (d) which was subtracted from the original data was manufactured with a 2 minute dark (a) and a 10 second dark (b).

d = [(17 / 11) * (a - b)] + b

Subtracting this dark really made a big difference as this was a pretty dim object before stretching the contrast. This picture was also the longest picture taken at the time. Being completely unguided, I'm pretty happy with it.