NGC/IC Project Restoration Effort

(This is a very very beta version)

NGC6939

 

Basic Information


Location and Magnitude


Right Ascension: 20:31:30.0
Declination: +60:39:42
Constellation: CEP
Visual Magnitude: 7.8

Historic Information


Discoverer: Herschel W.
Year of discovery: 1798
Discovery aperture: 18.7

Observational


Summary description: Cl, pL, eRi, pCM, st 11…16
Sub-type: I1m

Steve's Notes

===== NGC 6939 18" (10/9/04): beautifully rich cluster of ~150 stars in a 10'-12' triangular region over haze. Beyond the ends of the triangular vertices are four 10th magnitude stars with the star towards the ENE an easy double. The cluster is fairly uniform with a rich clump of a half-dozen stars near the center. A number of the stars are in chains, including a string of equally spaced 12-13th magnitude stars along the south side that is oriented NW-SE. NGC 6946 (which was sporting a supernova) lies 40' SE and both can be placed in the same low power field. Both objects are easily visible in 15x50 IS binoculars and of similar size, but NGC 6939 is brighter with a higher surface brightness. 18" (8/17/04): this triangular-shaped rich cluster is beautifully framed in the 160x field (24'). The cluster is enclosed within a kite asterism of four mag 10 stars with two of these stars near the east and west vertices of the triangular outline. ~125 stars are visible in a 10' diameter, with most of the stars mag 12-14. Just west of center is a very rich 3' group and just following this group is a small knot of 4 very faint stars. The west side is well-defined by a string of mag 12 stars oriented NW-SE. 17.5" (9/14/85): about 100-140 stars mag 12-15 are resolved. Difficult to count as stars fill the 22' field at 220x with no distinct boundaries. NGC 6946 is located less than 40' SE. 13" (7/27/84): ~80 stars resolved but richness makes an accurate count difficult. 13" (7/5/83): ~70 stars resolved at 166x, very rich, beautiful in faint stars.