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!


  1. This is outstanding work. I like the detail behind the image as it gives me something to ponder when I go outside and stare at the sky. Nice.



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