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NGC 2304 (4,378 of 18,816)

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NGC 2304

NGC 2304, Cl Collinder 120, C 0652+180, VI 2, h 415, GC 1467

RA: 06h 55m 0.9s
Dec: +18° 01′ 14″

Con: Gemini
Ch: MSA:178, U2:138, SA:12

Ref: SIMBAD, Collinder (1931), DAML02, Archinal&Hynes (2003)

(reference key)

Type: open cluster, 21m

Mag: B=?, V=10

Size: 3′
PA: ?

Historical observations

William Herschel (c.1784)

Synonyms: H VI-002

Discovered in 1785 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a very compressed cluster of extremely small stars, irregular form, 5 or 6' diameter."

Birr Castle/Lord Rosse

Observations with the 72-inch f/8.8 speculum telescope at Birr Castle noted "a poor cluster."

Published comments

Trumpler, R.J. (1928)

Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 4' and the class as 1 1 m.

Houston notes that this open cluster is within reach of "modest amateur telescopes." He notes that the cluster appears quite rich, and adds that it is distinctly oval and, according to the Webb Society's handbook for open and globular clusters, has a nebulous appearance at low powers.

Raab, S. (1922)

Raab, S. (1922) A research on open clusters. Lund Medd. Astron. Obs. Ser. II, 28, 1.

Discussed, based of F-A plates.

Vorontsov-Velyaminov, B. (1925/1926)

Vorontsov-Velyaminov, B. (1925) "Catalogue of integrated magnitudes of star clusters", Astron. Nach. 226.195. Comparing the brightness of the cluster with the extrafocal images of stars, he estimates the magnitude as 7.70.

Melotte, P.J. (1915)

A catalogue of star clusters shown on Franklin-Adams chart plates. Mem.R.A.S., 60(5), 175-186.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 11.0 mag open cluster.

Modern observations

Ancient City Astron.Club (1980)

Listed by the Herschel Club, described as "small, loose and irregular, stars of similar magnitudes, situated above a bright field star. 6-inch, 48x."

Tom Lorenzin

Tom Lorenzin, in the electronic version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "10M; 4' diameter; rich for its size; 20-plus faint members."

Steve Coe

Steve Coe, observing with a 13" f/5.6, notes: "Faint, pretty small, somewhat compressed. 11 stars in a 5 arc minute area. Curved "comma" shape to the cluster."

Brian Skiff

POSS: catalogued as gx U3583 = Z85-13 = M+3-18-02

Lick: string leading SW crosses NW side.

15cm - losfcbr cloud @ 50x, which shows *s at threshold w/attention. 140x: 4'

diam, only 18 *s res plus haziness. NW side flattened, bounded by

string of *s. stars m13.5-14 and fntr. BS, 7Nov1988, Anderson Mesa.

25cm - f cloud of 20 *s in 4' area. * chain leads SW from center. brtst *

m11.5.

30cm - 149x: partially res w/*s m13+. 238x: reveals5'.5x4' cl w/20 *s. some

unres haze NW side has def edge, while most of the outliers spread E and

NE. britr strong of *s on NW edge, extending into a point to SW.

Contemporary observations

Tom Bryant

2012 1 15 21:50:48

Observing site: Syria, Va

Telescope: C-11

[6h 55m 0s, 18 1m 0s] A cluster of around 50 12mv... stars in a very rich field. This would have been invisible at Little Tycho.

Richard Ford

2013 February 7th, Thursday

Location:Blesfontein Guest Farm,Sutherland.

Time:9:53pm.

Sky Conditions:The most crystal clear sky possible.Dark moon and stars magnitude 6 and fainter are visible with the naked eye.Excellent clean sky,limited star flickering and brilliant objects.

Instrument:12-inch Dobsonian.

This open cluster has a misty appearance whereby I have counted 22 stars within a fixed diameter and I have noticed that this cluster consists of 11.8 magnitude stars.The stars in this cluster however are orientated in a north east by south west position.In this open cluster most of the stars are nearly the same brightness as each other and that the stars in this cluster are concentrated towards each other.Finally I have noticed that the stars in this open cluster are well detached.This open cluster measures 6.2'x4.4'.Chart No.208,NSOG Vol.1.

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