NGC 7331 (September 2017)

NGC 7331, the big galaxy in this image, appears in our constellation Pegasus.  The galaxy is roughly 47,000,000 light years away.  We see its spiral shape at a dramatic angle.

Equally intriguing are the smaller background galaxies.  Across the upper part of the image, NGC 7337, NGC 7335, and NGC 7336 float over 7331 like seagulls about to dive.  NGC 7337 and 7335 lie far in the background, probably ~300,000,000 light years away from us, over 6x further than 7331.  NGC 7336 is another hundred million light years further still.

Besides these, the image shows numerous other bits of fluff—galaxies all, many of which may be even further away.  Including the large systems, I count at least fifteen galaxies in the image.  Some of these are far in the background.

In addition to the galaxies, the image shows many stars in our own galaxy.  Stars as dim as magnitude 20 appear in the frame.

This image was taken in four sessions in September 2017, and is 66x720" (13.2 hours) with the SXVF-H9 through the CFF 290 Classical Cassegrain at f/8.11, an effective focal length of 2353mm.  The frames were shot through an Astronomik CLS filter from a red zone.

NGC 7331, Stephan's Quintet (Sept. 2015)

NGC 7331 in its glory, and all the little galaxies.

NGC 7331 is about 48 million light years away (based on studies of its Cepheid variables).  The galaxies above and behind NGC 7331 are far in its background, but they are probably relatively near to each other.

The group of galaxies to the lower left is called Stephan's Quintet, after its discover.  It is also called Hickson 92, after a cataloger of odd galaxy groups.  And this one is odd.  The oval on the left (NGC 7320) is in front of the others.  In the Hubble image of this group, that oval galaxy is blue.  Its red-shift suggests that it is only 35 million light years away---somewhat near NGC 7331 and thus not a member of the group.  The other galaxies in the area, however, are closer to 270 million light years away, far in the background.  Those background galaxies are gravitationally connected to each other.

There is a small galaxy above Hickson 92, and one tidal tail from the 92 group reaches up toward it.  This galaxy, NGC 7320C, is also connected to the Hickson 92 group and probably moved through it millions of years ago, causing the tidal tail.

Telescope: Astro-Tech AT111EDT and William Optics AFR-IV (eff. f/5.6)
Camera and Exposure: SXVF-H9 (107x420"); Alnitak Flat-man flats
Filter(s): Astronomik CLS
Guiding: SX Lodestar and SX OAG
Mount: Takahashi NJP
Software: Nebulosity, PHD, SkySafari, Maxim DL, Photoshop CS3
Location: The Woodlands, TX

NGC 7331 & Companions

I woke up to check the final images on the Crescent Nebula set and found the sky temporarily clouded over. When the sky cleared five minutes later, the Crescent was slipping into the trees. The constellation Pegasus, however, was just overhead! I had observed NGC 7331 before with an 8" dobsonion, but I have always wanted an image of it. "Well, the sky is still dark! Why not tonight?" NGC 7331 is 50 million light years away. The galaxies surrounding it (which I had never seen before) are probably ten times further, or 500 million light years away. See other very nice, color images of all of them here and here.

This set of images, 45x2', began at 4:10 a.m. It was processed in Nebulosity 1 and Photoshop Elements 7. It could use more processing, but I do not own the software for more, yet.