sponsored by psychohistorian.org

DOCdb

Deep Sky Observer's Companion – the online database

 

Welcome, guest!

If you've already registered, please log in,

or register an observer profile for added functionality.

List:

log in to manage your observing lists

 browse:

 

 position:

 

 next:

 

 options:

summary

rename

prune

trim

remove

close

copy

combine

plan

bookmark

load

new

delete

marathon

favourite!

Full database:

Entire DOCdb database of 18,816 objects.

 browse:

 position:

NGC 6913 (16,231 of 18,816)

 next:

oc gc pln bn dn gx gxcl ast aka lost

Object:

list

bookmark

finder chart

altitude today

altitude (year)

 search:

½°, , in DOCdb

show browsing

Cooling Tower

NGC 6913, Cl Collinder 422, C 2022+383, OCISM 36, Ocl 168, COCD 488, Messier 29, Cooling Tower, h 2078, GC 4576

RA: 20h 23m 56s
Dec: +38° 31′ 24″

Con: Cygnus
Ch: MSA:1148, U2:120, SA:9

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

(reference key)

Type: open cluster, 23mn

Mag: B=7.3, V=6.6

Size: 10′
PA: ?

Remarks

It is a member of the Cygnus OB 1 Association.

Historical observations

William Herschel

In the Appendix to the 1912 'Scientific Papers of Sir William Herschel' this object is described as "1794, October 27, Is not sufficiently marked in the heavens to deserve notice, as 7 or 8 small stars together are so frequent about this part of the heavens that one might find them by hundreds."

Published comments

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 7.13.

Trumpler, R.J. (1928)

Trumpler (Lick Obs Bul, Vol 14, No. 420) gives the diameter as 7' and the class as 3 3 p.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag open cluster.

Boeche, C. et al. (2003)

"NGC 6913 .. is a young open cluster harboring O-type members and lying close to the plane of the Galaxy... Despite appearing in the Messier catalog as M29, few papers in literature deal with it, furthermore showing some disagreement in the results."

Cluster distance estimated range from 1.1 kpc to 2.2 kpc; "Tifft (1958) suggested that NGC 6913 is indeed the result of two separate groups of stars, one at 1.6 kpc and the other somewhere between 1.9 and 2.4 kpc."

Estimated ages span from 0.3-1.75 Myr to 10 Myr.

Reference: Boeche, C. et al. (2003) Kinematics and binaries in young stellar aggregates. II. NGC 6913=M29. arXiv:astro-ph/0310090v1

Modern observations

Tom Lorenzin

Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7M; 7' diameter; 20-plus 8 thru 11M members; all blue-white; 7 brightest stars form 2 opposing, symmetrical curves; cluster N6910 (6.5M; 8' diameter) 2 degrees due N; 25' NNE of 3M Gamma CYG; surrounded by 2-part nebulosity I.1318; cluster I.1311 2 degrees W of N6910; reference-VADSS-217."

MacRobert, Alan M

MacRobert writes: "M29 is arranged in a unique shape. Seven of its brighter stars form two small arcs bowing toward each other like the outline of a power plant's cooling tower. There are supposed to be 50 stars here, but I certainly don't see that many with my 6-inch. What is apparent, however, is that this whole region is heavily obscured with dark clouds blotting out patches of the Milky Way background. Suspicious dark zones lie just east and north in particular."

Gramer, Lew (IAAC)

Observer: Lew Gramer; Your skills: Intermediate; Date and UT of Observation: 1997-07-25/26, 04:00 UT; Location: Medford, MA, USA (42N); Site classification: urban; Limiting magnitude: 5.8 (zenith), intermittent haze; Seeing: 5 (out of 10 highest) - mediocre; Moon up: yes, 50% (not visible at site); Instrument: 7x50mm Simmons binoculars

Distinct bright haze just 1/2 a binocular field (less than 3o) SSE of gamma Cyg, and about 40' due W of a mag. 6 star, which is found immediately SE of gamma. Unmistakable, even in this sky! Diffuse, with no concentration apparent, although a stellaring of near-resolved stars was visible on the S edge.

Brian Skiff

6cm - sm, pretty cl of br *s. 12 *s vis w/a little haze. six brtr ones. immed fld is pretty blank.

7cm - sm sparse cl w/only brtr *s, not real well sep from fld @ 30x. 75x: 15 *s in 5' diam, mostly m8-9. BS, 27Nov1992, Anderson Mesa.

15cm - H shape suggested 15 *s. elong SE-NW, 8' diam. fairly distinct from fld by compactness and geometry.

- sparse isolated by dk Rift to E. many more bkgrnd *s starting at W edge of cl. 140x shows 25 *s in 4'-5' area incl six of m7-8. BS, 15Oct1990, Anderson Mesa.

20cm - kind of sm. esembles M18; a few br *s upon a rich fld. 20 *s m8-10 in 10' area.

25cm - sm and loose w/only a few br *s. box shape outstanding w/other pairs and shapes.

- 90x: 26 *s in 6' area.

30cm - 21 *s in 10' area. six brtst *s are in two arc NE&SW, concave outward like so: )(. br part of cl 6' across.

Contemporary observations

Auke Slotegraaf

1983

Observing from Stellenbosch, 1983, I used a 2-inch refractor and wrote: "Two bright stars involved. Brightest star double; secondary faint and close. Other stars in cluster difficult to see; with averted vision 2 or 3 stars can be glimpsed to sparkle out. Very difficult -- nebulosity around bright star." The size was estimated as 9'.

Magda Streicher

(no date)

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

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

Cluster eight stars are arranged in the form of a backwards "K". This lovely handful of stars is very boxy with the southern part more define and busy. 5.5' more or less in size.

Favourite lists

Lacaille's catalogue

The Messier objects

Dunlop's catalogue

The Bennett objects

The Caldwell list

Named DSOs

Object search

First search phrase

    and

Second search phrase

Type of object to include:

open cluster
globular cluster
planetary nebula
bright nebula
dark nebula
galaxy
galaxy cluster
asterism & stars
unverified/lost
nova

The Bug Report

DOCdb is still in beta-release.

Known issues, feature requests, and updates on bug fixes, are here:

> Bug Report

Feedback

Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!

> Contact us

Help!

DOCdb is a free online resource that exists to promote deep sky observing.

You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.

> Find out more

Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.