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Cl Trumpler 7 (4,633 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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Cl Trumpler 7

Cl Trumpler 7, C 0725-239, Cl Collinder 146, Ocl 635, COCD 140

RA: 07h 27m 21s
Dec: −23° 57′ 24″

Con: Canis Major
Ch: MSA:344, U2:319, SA:19

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

(reference key)

Type: open cluster, 23mn

Mag: B=8.02, V=7.9

Size: 5′
PA: ?

Published comments


Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 5.5' and the class as 2 3 p. He notes: "Mentioned by Barnard (Bd.Atl. pl10). Well defined dense clustering of 20-30 stars 10-15th mag, slightly irregular."

Vogt. N. & Moffat, AFJ (1972)

Vogt. N. & Moffat, AFJ (1972), "Southern Open Star Clusters I." Astron.Astrophys.Suppl., 7, 133-167. [image, table]

They conclude the distance is 1.62kpc and note that it "lies in the local arm of the Galaxy."

Modern observations

Steve Coe

Steve Coe, observing with a 13" f/5.6, notes: "Pretty faint, pretty small, not rich, somewhat compressed, 17 stars counted at 135X."

Brian Skiff

25cm - consp @ lox, dominated by a string of *S aligned SE-NW that incl two

pairs nr the center and a f triple at the NW end. 10'-12' long w/25 *s

incl immed area around string. two brtr *s, m9-10. BS, 25Jan1982,

Anderson Mesa.

Contemporary observations

Auke Slotegraaf


This small cluster can be seen whilst sweeping with a 10-inch f/5 at 30x as a nebulous patch. It has two 9th mag stars on its northern border, and the rest of the cluster seems to extend away to the south and east of these. At 30x it appears poor, consisting of faint members. 120x shows an additional three small stars between the two 9th mag stars, and the south-eastern extension is seen as a straight line of four or five stars. Counting the considerably faint stars, I would geustimate the cluster has 15 members.

Magda Streicher

2006 November 20


16-inch f/10 SCT (127x, 290x)

Just NE from Trumpler 6 and slightly more outstanding with a elongated shape in a N-S direction. The grouping display brighter stars in the northern part, a short string in a NW-SE direction. From there down south the grouping shape down in a stringy shape for almost another 4'. Towards the SE of Trumpler 7 a triangle of three 9-magnitude stars can be seen spaced 3' between the members.


(no date)

Alldays (22.50S, 20.12E, 770m).

12-inch f/10 SCT (95x, 218x)

Trumpler 6 as I see it only shows a few faint stars in 'n knot but slightly elongated in a NW-SE direction. Trumpler 7 is a string grouping in a N to S direction with the brighter stars to the northern side, and what a nice show piece of stars.

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