Showing posts with label Asterism. Show all posts
Showing posts with label Asterism. Show all posts

Sunday, July 6, 2025

Cr 399 - The Coathanger Asterism - Wide Field

 I'll Say it again; this is a great target to observe using binoculars ...

Monday June 23rd was forecast to be a clear night (the second clear night in a row). I was able to get my astrophotography rig set up before dark. Since we were so close to New Moon, I looked for a broadband target that would get high above the trees that obscure my horizon and would be appropriate for my wide field set up. Collinder 399, The Coathanger Asterism fits the criteria. The only thing that gave me pause is that I imaged this target previously, at a longer focal length (click here to view the blog post). After looking at this target in the Framing Wizard in NINA, I decided to go for it. 

Targets like this one are not as "exciting" as emission nebula or galaxies, but I'm always overwhelmed by the enormous number of stars contained within the field. Furthermore, The Coathanger is a great target to observe using binoculars. Regardless of whether you are an experienced amateur astronomer with many telescopes or you are just getting started with astronomy, binoculars are super useful for observing. Most people have access to binoculars, and they are a great way to get started in the hobby. I have a pair at home and a pair I keep in my truck. This target is very easy to find (see the "How to Find" section below). I never get tired of looking at it.

The evening went relatively well. I got everything set up and connected. After polar aligning the mount and calibrating PHD2, I began the imaging sequence. The first sub came in at 10:42 PM. I went to sleep, soon after that. The rig continued to collect subs until 3:58 in the morning. Here's the resulting image.

Collinder 399, also called the Coathanger Asterism or Brocchi’s Cluster, photographed on June 23, 2025, from a backyard in Eden, NY. The image shows a prominent coat hanger shape—six bright stars in a line with a curved arc above—set in a wide field of stars in the Cygnus region.
An image of Cr 399 - The Coathanger, captured from my backyard on 06/23/2025

Processing:

All pre and post processing was performed in PixInsight. Pre-Processing: All subs were visually inspected with Blink and subs with issues were removed. All light Frames, Flats, Darks and Dark flats were loaded into WBPP. Linear Post Processing: Background extraction was performed with GraXpert followed by BXT (correct only). SPCC was used for Color Calibration followed by a full application of BXT. The Stars were removed using StarXT. Starless Linear: Noise was reduced with NXT. The image was made non-linear with HT. Linear Stars: The stars were made non-linear with Seti Astro's Star Stretch Script.

Non-linear Post ProcessingStarless: Color, intensity, and contrast were adjusted with various applications of CT. Saturation was increased with CT. The DSE script was used to enhance dark nebula regions. Stars: Saturation was increased with CT. Final: The Stars and Starless images were combined with Pixel Math to produce the final image. CT was used to adjust contrast one last time.

What is it?

The Coathanger is known as Collinder 399 (Cr 399) or Brocchi's Cluster. This object is an Asterism (a prominent or recognizable pattern of stars). It is not a true open star cluster, it is a chance alignment of 10 bright stars. There are about 30 more stars that some consider to be a part of the asterism. 



An annotated image of Cr 399.

How big is it?

This object has an angular distance of 89 arcminutes (1 degree is 60 arcminutes) on the night sky.

How far is it?

It is located about 4,200 light-years (ly) from Earth in the Constellation Vulpecula.

How to find it?

This is object is relatively easy to find in a pair of binoculars, optical finder scope, or telescope with a wide field of view. It is located in the Constellation Vulpecula which is a dim constellation located within the Summer Triangle.  Use the finder chart below to help you locate it.

  1. Find the Summer Triangle (Vega, Deneb, & Altair).
  2. Method 1: 
    1. Find Albireo (a beautiful visual target itself) which is the head of Cygnus the Swan or the base of the Northern Cross. 
    2. Find the star Alpha Vulpecula and draw an imaginary line from Albireo through Alpha Vulpecula. The Coathanger is roughly the same distance from Alpha Vulpecula as Alpha Vulpecula is from Albireo. 
  3. Method 2:
    1. Find Vega and Altair and draw an imaginary line between them.
    2. The Coathanger is roughly between both stars (it's a little closer to Altair).
Finding Chart for Cr 399

Image Details:

Capture Date: 6/23/2025
Location: Eden, NY
Telescope: Askar FMA180 Pro
Camera: ZWO ASI2600MC Pro
Filter: N/A
Mount: Sky-Watcher USA EQ6-R Pro
Exposure: 221 exposures at 60 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of almost 3 hours and 41 minutes.
Software: NINA, SharpCap Pro, PHD2, and PixInsight


Clear Skies!
Ernie

Sunday, September 10, 2023

The Coathanger Asterism - A Great Target for Binoculars

 

Things have been a little crazy

It's been a while since I've posted. In addition to poor weather and smoke, the last couple of months have been crazy (both at work and at home). Catching up on the few opportunities I had to image since July.

The Coathanger - captured on 8/19/20232 with the open star cluster NGC 6802 just to the left of the horizontal portion of the Coathanger.

The Coathanger is one of my favorite visual targets, especially for binoculars (this isn't the first target or the last that I will describe in that way). I love to observe with binoculars. I have a pair of 8 x 40 and a pair of 10 x 50. The 8 x 40's are perfect handheld and the 10 x50's are best on a tripod. The Coathanger is located in the Summer Triangle, so it is almost directly overhead at dark. If you're interested in astronomy and don't have a telescope (or even if you do), but have a pair of binoculars, grab them at dark and try finder this object. 

August 19th was a Saturday night. Although clear, the transparency was poor and clouds were predicted later in the night. Only a brief window to image. Knowing the window would be short, figured I would go after The Coathanger as lots of integration time would not be needed. Ended up with 92 subs at 30 secs each. I started collecting subs at 9:55 PM and stopped at 11:23 PM when the clouds became more frequent. I collected 119 subs but had to discard a large number due to passing clouds / poor sky conditions. Given the circumstances, the resulting image isn't that bad. 

What is it?

The Coathanger is known as Collinder 399 (Cr 399) or Brocchi's Cluster. This object is an Asterism (a prominent or recognizable pattern of stars). It is not a true open star cluster, it is a chance alignment of 10 bright stars. There are about 30 more stars that some consider to be a part of the asterism. 


An annotated version of the image of The Coathanger.

How big is it?

This object has an angular distance of 89 arcminutes (1 degree is 60 arcminutes) on the night sky.

How far is it?

It is located about 4,200 light-years (ly) from Earth in the Constellation Vulpecula.

How to find it?

This is object is relatively easy to find in a pair of binoculars, optical finder scope, or telescope with a wide field of view. It is located in the Constellation Vulpecula which is a dim constellation located within the Summer Triangle.  Use the finder chart below to help you locate it.

  1. Find the Summer Triangle (Vega, Deneb, & Altair).
  2. Method 1: 
    1. Find Albireo (a beautiful visual target itself) which is the head of Cygnus the Swan or the base of the Northern Cross. 
    2. Find the star Alpha Vulpecula and draw an imaginary line from Albireo through Alpha Vulpecula. The Coathanger is roughly the same distance from Alpha Vulpecula as Alpha Vulpecula is from Albireo. 
  3. Method 2:
    1. Find Vega and Altair and draw an imaginary line between them.
    2. The Coathanger is roughly between both stars (it's a little closer to Altair).


A finder Chart for The Coathanger

Image Details:

Capture Date:08/19/2023
Location: Eden, NY
Telescope: Explore Scientific ED80 Essential Series Air-Spaced Triplet Refractor
Camera: ZWO ASI2600MC Pro
Filter: none
Mount: Sky-Watcher USA EQ6-R Pro
Exposure: 92 exposures at 30 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 46 minutes.
Software: NINA, SharpCap Pro, PHD2, and PixInsight


Clear Skies!
Ernie

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