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Cl Collinder 399 (15,723 of 18,816)

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Al Sufi's Cluster

Cl Collinder 399, C 1923+200, Ocl 113.0, Coathanger, Brocchi's Cluster, 4-5 Vulpeculae Cluster, Al Sufi's Cluster

RA: 19h 26m 12s
Dec: +20° 05′ 33″

Con: Vulpecula
Ch: MSA:1220, U2:161, SA:8

Ref: SIMBAD, [1998A&A...340..402B], Archinal&Hynes (2003)

(reference key)

Type: asterism, 33m

Mag: B=3.93, V=3.6

Size: 90′
PA: ?

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Photos  (1)

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Remarks

Also known as the Coat Hanger, this very large loose grouping of stars includes the stars 4, 5 and 7 Vulpeculae. It is one of the oldest clusters on record, being observed in the 10th century by the Persian astronomer al-Sufi. It is a favourite binocular object. The Coathanger's hook extends south from the middle of an east-west line of stars 1.5 degrees long.

Published comments

Roslund

Roslund, C. (1960) "Remarks of some new and some known galactic clusters", p 205-207

"The brightest stars in the field is 5 Vulpeculae, a dwarf of type B9. Next in brightness are three stars of type B9 III, G8 III, and A0 IV, followed by main sequence stars from A2 to A7."

Modern observations

Walter Scott Houston

Houston writes: "The cluster has a most unusual shape. A straight line of six 5th- and 6th-magnitude stars runs exactly east-west, while another four form a small hook extending southward from the middle of the line. The group is quite striking in binoculars and looks very much like an inverted coathanger."

Harrington, Phil

Harrington writes: "On exceptional nights the naked eye can pick out the brightest stars that make up the celestial coathanger (4, 5 and 7 Vulpeculae), but binoculars are needed for a good view. Seven-power glasses easily show the row of six stars that form the coathanger's crossbar, while four others curve away to mark the hook. In all, Cr 399 contains some five dozen stars spanning a full degree of sky."

Tom Lorenzin

Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "3.6M; 1 degree extent! celestial "Coat Hanger"; binoculars best; OPN CL N6802 (11M; 4' diameter) on E edge, a neat silver sprinkle."

Rick Raasch

Rick Raasch writes in "The Focal Point", Volume 6, No. 1 (1993) "This star cluster is easily seen with the naked eye with its distinctive star pattern. A cruise though it with binoculars reveals many bright stars and star fields."

Contemporary observations

Auke Slotegraaf

2010 August 06/07, Fri/Sat

Karoo Star Party, Britstown, Northern Cape, ZA.

SQM-L 21.2

15x70 Celestron binoculars.

Another binocular treasure, not too far from the Dumb-bell. A large, poor cluster of bright (~ 6V) stars, six of which lie in an almost-straight line running east-west. It's distinctive angular shape mimics nearby (5) Sagitta.

Richard Ford

2010 August 7, Saturday

Location:Kambro Padstal,Britstown.

Instrument:12"Dobsonian Reflector Telescope.

Sky Conditions: Dark moon and stars magnitude 6 and fainter are barely visible with the naked eye.

Transparency of the Sky:The most clear sky possible.

Seeing:Excellent clean sky,limited star flickering and brilliant objects.

Limiting Magnitude:6.5.

First Impression:Open Cluster.

Location:Vulpecula.

Time:10:15pm.

Chart Number:No.6(Extract taken out of "Atlas of the Night Sky").

Size:26mm Eyepiece:Field of View:57'/1=57'

20mm Eyepiece:Field of View:50'/1=50'.

57'+50'=107'.

107'/2=53.5'.

Size in Arc Minutes:53.5'.

Ratio:1:12.

Major Axis:53.5'.

53.5'/12=4.4'.

Minor Axis:4.4'.

Open Cluster is 53.5'*4.4'.

Brightness:Bright.

Brightness Profile:High Surface Brightness.

Challenge Rating:Spectacular to observe this large open cluster under a very dark sky.

Description

-----------

By observing this open cluster, the stars in this cluster is separated from each other.The stars in this cluster is well arranged in the shape of a coathanger.In overall I have found 20 stars in this open cluster. I have found that most of the stars in this cluster are nearly the same brightness as each other. In overall the stars in this cluster is not concentrated towards each other.

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