NGC 7331 and Two Galaxy Groups: The Deer Lick and Stephen's Quintet
Date: August 23, 2020
Cosgrove’s Cosmos Catalog ➤#0049
The Deer Lick group is the group on the upper left. The large galaxy is NGC 7331. In the lower right is the famous galaxy group known as Stephen’s Quintet. (click to enlarge)
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About the Target
These two galaxy groups are found in the constellation Pegasus. Some are located at extreme distances from Earth.
Stephan's Quintet, the group of 5 small galaxies in the lower left of the frame, was the first compact galaxy group ever cataloged by Edouard Stephens in 1877. The group consists of 5 galaxies: NGC 7317 is an elliptical galaxy. NGC 7318 Is actually two galaxies that are converging, and they show sides of distortion. NGC 7319 is another interacting spiral galaxy. Finally, NGC 7320 is the brightest of the group with a blue coloration. This is because four of the galaxies are actually from a common cluster - these are all 300 Million light-years away. However, the bright blue one is only 60 Million Light years away, so it is really a galaxy that happens to be in the line of sight.
The other group, located towards the top left, is the Deer Lick Group. Why the "Deer Lick Group" ? - no idea! The Largest galaxy seen here is NGC 7331. This spiral galaxy is located about 46 Million Light years away and was discovered by Sir William Hershel in 1784. It was the brightest object that was missed by Messier when he was making his famous catalog. NGC 7331 is very similar in size and structure to our own Milky Way Galaxy. The other group members consist of NGC 7331 in this shot, including NGC 7335 and NGC 7337, which are smaller Spiral galaxies. I have heard the smaller galaxies called the “Fleas” - does that make the large galaxy the deer?
Annotated Image
Annotated image of the Deer Lick and Stephen’s Quintet was created with Pixinsight’s Imagesolver and AnotateImage scripts.
Location in the Sky
IAU/Sky & Telescope Constellation Chart of Pegasus with the location of the galaxy groups indicated by a yellow arrow.
About the Project
Hot off the presses from my photo session last night: NGC 7331 and Two Galaxy Groups: The Deer Lick and Stephen's Quintet.
There are plenty of star clusters out there, but I was interested in shooting a cluster of Galaxies. Stephen's Quintet is high enough in the sky this time of year that it clears my trees about midnight, so I started to put together a plan to go after that. I soon realized that I could get two for the price, as The Deer Lick Galaxy with NGC 7331 was not too far away.
I used the Mosaic and Framing tool in Sequence Generator Pro to access my ability to frame both groups in the same frame. It not only looked like it would fit, but it also allowed me to lay out just the framing I was looking for.
The SGP centering operation would ensure that the center of the field was lined up and would work with the Falcon Camera Rotator to ensure the framing was right.
This image was the result of 90 x 150-second subs.
Previous Effort
I have shot the NGC7331 group on one previous occasion.
The version shot in 2019 can be seen HERE.
A side-by-side comparison can be seen below.
October 2019 version (Click to zoom)
Current Version (Click to zoom)
More Info
Wikipedia: NGC 7331
Wikipedia: Stephen’’s Quintet
NASA: Hubble Images of Stephen’s Quintet
The Sky Live: NGC 7331
The Sky Live: Stephen’s Quintet
Capture Details
Lights
90 x 150 seconds, bin 1x1 @ -15C
Cal Frames
50 x 2 second Bias exposures
25 x 150 second Dark exposures
50 Flats
Capture Hardware
Scope: William Optics 132mm FLT F/7 APO
Guide Scope: Apterna 60mm
Camera: ZWO ASI294MC-Pro
Guide Camera: ZWO ASI290Mini
Focus Motor: Pegasus Astro Focus Cube 2
Field Rotator: Pegasus Astro Falcon
Mount: Ioptron CEM60Polar Alignment: Ioptron Ipolar integrated alignment cameras
Software
Capture Software: Control: PHD2 Guider, Sequence Generator Pro controller
Image Processing: Deepsky Stacker, Pixinsight, Photoshop, Coffee, extensive processing indecision and second guessing, and much swearing…..
During the Summer of 2020, whilst stuck at home because of Covid I became very in improving the automation of the platform and achieving a more precise framing of the shots I made…