NGC 6846 (Lund 912, Cr 410) Open Cluster in Cygnus

Located at: RA 19 hours 56 minutes 28 seconds, Dec +32 degrees 20 minutes 55 seconds

Size: 0.8' Magnitude: 14.2 visual Class: II 2 -- (IV 1 p)*

North is up

West to the right

Telescope:

8" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -15c, camera control MaxIm DL 4.56

Image:

Lumicon Deep Sky filter, 300 minutes (30 x 10 minute subs), 08/2/3/2007

Processing:

CCDStack 1.2, Photoshop 7.0

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes:* According to "Star Clusters", by Brent Archinal and Steven Hynes, this little open cluster has had a positional error of 2 degrees too far south in most references published since 1931 (by Collinder ... Collinder 410).

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 6846
NGC 6846 = Lund 912 = OCL-139 = Cr 410
19 56 28.1 +32 20 58
V = 14.2;  Size 0.8

17.5": at 225x appears as a small, faint clump of stars over unresolved haze.  
Elongated about 3:2 E-W with dimensions 1.5'x1.0'.  A mag 13.5 star is off the 
NW edge, a mag 14 star is at the W edge and three additional mag 14 stars in a 
clump are just visible over of the haze although clean resolution is difficult.  
The extremely faint stellar planetary K4-41 is 2' NE!  The position given in 
RNGC, Lynga, N2000 and U2000 is exactly two degrees too far south.

Discovered by Stephan and correctly placed at 19 56 28.7 +32 21 16 (2000).  RNGC 
lists this open cluster at 19h 56.5m +30 21 (2000) or two degrees south of 
Stephan's position and I unsuccessfully searched for the cluster at this 
position with my 17.5" scope.  The incorrect position in the RNGC is also found 
in the Lynga #5 catalogue (source of the orignal error?) and is repeated in NGC 
2000, DSFG and on the U2000 star atlas.  Listed in RNGC Corrections #6.  See 
Corwin's NGCBUGS.

- by Steve Gottlieb
Historical Research Notes / Correction for NGC 6846
NGC 6846.  The RNGC position is 2 degrees too far south.  At the correct
position is a compact little cluster matching Stephan's description exactly:  
the three brightest stars are clear enough that he could see them, but the 
others are considerably fainter, so the entire group must have looked quite 
nebulous to him. - Dr. Harold G. Corwin, Jr.

 There is a very small (3") Planetary Nebula (PK68+1.1) about 1.9 minutes NNE of this cluster (looks like a small star at this focal length)