NGC 189 (Cr 462, Lund 23) Open Cluster in Cassiopeia

Located at: RA 00 hours 39 minutes 36 seconds, Dec +61 degrees 05 minutes 42 seconds

Size: 3.7' (5.0') Magnitude: 8.8 Class: II 1 p

North is up

West to the right

Telescope:

 14.5" f5 Newtonian reflector

Camera:

  ST-8XME, self-guided, binned 1x1, temp -20c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 480 minutes (48 x 10 minute subs), 10/01/02/2017; seeing 2.5-4.1 FWHM per CCDStack

Processing: CCDStack 2.94.6355.18107, Photoshop CS5.1
Location:

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

Notes: Beginning of October ... mostly clear weather, fairly poor seeing (with the advent of off-shore winds), and the brightening moon led me to imaging some open clusters (see NGC 433 and Riddle 4) in the north.

According to  "Star Clusters", by Brent Archinal and Steven Hynes, the size of this open cluster is listed as 5.0 arc minutes ("Skiff: Diameter 3.7' too small").

From the NGC / IC Project:

NGC 189 = Cr 462 = OCL-301 = Lund 23

00 39 36 +61 05 42

V = 8.8;  Size 4'

24" (1/4/14): well detached, roundish group of stars at 125x.  Using 260x, ~40 stars are resolved in a 5'-6' group.  There are several pairs and tight groupings.  Many of the stars are in a richer 3' inner group, generally arranged in a ring and including h 1043 = 11.6/12.7 pair at 12" (oriented N-S).  A few of the brighter stars, though, form the 6' outline.  A distinctive quadrilateral of stars is ~6' NW.

17.5" (11/27/92): 30 stars mag 10-14 in 6' diameter, weakly compressed, no dense areas but appears to have some unresolved background haze.  Elongated E-W due to a couple of strings extending to the west.  A 6'x5' parallelogram of four mag 9 stars in the field to the south.  Not an impressive cluster.

8" (11/13/82): about two dozen stars, moderately large, irregular shape, scattered, haze.

Caroline Herschel probably discovered NGC 189 = h36 on 27 Sep 1783 although William attributed here with the discovery of NGC 381.  This is unlikely as the object she found preceded Gamma Cas, while NGC 381 follows.  WH made no observations and JH independently rediscovered the cluster on 27 Oct 1829 and described a "Cl, L; p rich; irreg R; 8' diam; straggling; *s 11...15m."