NGC 7331

Sketch of NGC 7331

Sketch of NGC 7331

Observation Notes:

I have glanced at and passed over this galaxy a number of times on my way to other nearby sights, such as Stephan’s Quintet. On this evening, I finally settled down for a nice, long look at it. Although I would have loved to make this observation from a dark site, I’m taking what I can get these days. So I observed from my back yard. There is increased sky glow from the Flagstaff Mall expansion, and some incidental reflected light to deal with, so conditions weren’t ideal. However, for in-town viewing in general it was pretty good. Anyway, those are my excuses. Here’s what I saw.

With the Pentax XW10 eyepiece (my 2nd sketch with this EP), I had a nice, wide field to frame the galaxy. At a first glance, the galaxy was obviously elongated, but definitely not as large as I anticipated. The larger, outer reaches had to wait a bit for my eyes to adapt better to the dark, spacious recesses of the eyepiece*. As the larger, elliptical shape gradually emerged, it offered a richer view of the galaxy’s overall form. It appeared to be elongated at a PA of 165° and was about 6 x 2 arc minutes in size. The bright core had a steep drop in brightness along its west side. The contour of this luminosity decrease appeared to curve just west of the midline and extend toward the tips of the ellipse. On the other side of this contour, a softer glow extended further westward to fill out the elliptical shape. The core itself had a mild plateau in brightness and it’s heart was stellar in appearance. To direct vision and to mildly averted vision, the bright, elliptical region surrounding the core was the only part visible. With more extreme averted vision however, the outer rim of the galaxy simply blossomed into view. It really is a magnificent sight–if you enjoy averted vision delicacies.

I was not able to extract further detail, or pick up any of the nearby ‘fleas’, but I was very pleased by the overall appearance that the galaxy offered–something like a much smaller M31. My daughter spent some time with me during the observation, talking about a new gobbledygook code language she’s inventing, and about a friend at school who is really getting interested in astronomy. Reminds me that I need to schedule time to visit the kids’ classes this year and do an astro presentation & hopefully daytime moon viewing.

*Can you tell I love this eyepiece? I don’t consider myself an equipment junkie, but this really is a fantastic observing tool.

Object Information:

NGC 7331 is the brightest member of the NGC 7331 galaxy group, also known as the Deer Lick Group. It was discovered by Friedrich Wilhelm Herschel in 1784. It is also cataloged as: UGC 12113, MCG+06-49-045, H I-53, h 2172, GC 4815, CGCG 514.068, PGC 69327

Subject NGC 7331
Classification* Galaxy (Sb I-II)
Position* Pegasus [RA: 22:37:04.5 / Dec: +34:25:01]
Size* 10.5′ x 3.7′ (PA 171°)
Brightness* 9.7 vMag (10.3 bMag)
Date/Time NOV 30 2008 – 08:30 MST (DEC 1, 2008 – 03:30 UT)
Observing Loc. Flagstaff, Arizona, USA – Home
Instrument Orion SkyQuest XT8 (203 mm dia./1200 mm F/L)
Eyepieces/Mag. Pentax XW 10 (120X)
Conditions Clear, calm, cold
Seeing 5/10 Pickering
Transparency ~ Mag 6.0 NELM

2 Replies to “NGC 7331”

  1. It was definitely a captivating sight, Ewan. The different areas that manifested themselves as I moved my eye around the field were fascinating. Eventually, I’ll make a dark site observation of this one, and I’ll probably be even more impressed with it. Thanks for the comment!

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