Collinder 399 – Al Sufi’s Cluster, Brocchi’s Cluster, The Coathanger

Bordering between the constellations, Vulpecula and Sagitta. This randomly formed cluster of stars forms the shape of a coathanger giving it it’s common name, The Coathanger. Discovered in 964 by a Persian astronomer by the name of Al Sufi, and mentioned in his book, Book of Fixed Stars. Later it was idependently rediscovered by an Italian astronomer named Hodierna in the 17th century. In 1920 an amateur astronomer named Brocchi created a map of the Coathanger and used it for calibrating his photometers. In 1931 a Swedish astronomer named Collinder added this to his catalog of open clusters.

Enlarge image, the coathanger can be seen near the middle of the screen shot.

Enlarge image, the coathanger can be seen near the middle of the screen shot.

These stars are were though to be an open cluster up until the late 20th century when it was determined that it is not an open cluster, but just a chance alignment of stars. 10 stars make up the Coathanger and they range from 5th to 7th magnitude with a straight line of 6 stars and 4 forming the hook. In dark enough skies this can be seen with the unaided eye or with a pair of binoculars. This large object is best seen with low magnification since the higher magnification used the more stars of the cluster are cut off from the asterism itself.

Coathanger without street light blocked

Coathanger without street light blocked

Coathanger with street light blocked

Coathanger with street light blocked

 

 

 

 

 

 

These images were taken from my front yard where I have a very bright street light. Two images above show a comparison of me blocking the light from the street light while imaging, and the other image shows an image without blocking the light. Neither image has been edited, only converted from a RAW file to a JPEG.

Collinder 399. 07-06-13

The above image is only 4 images with an exposure of 1 minute a piece, and ISO 800, I used 25 dark frames to remove as much noise as possible.

Screenshot of object location taken in Stellarium. Image stacking in Deep Sky Stacker.

Equipment:
Omni XLT 150 with CG-4 mount
Modded Canon 350D
T-ring and adapter
Intervalometer
Polar Scope for alignment

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