NGC 1981 (Lund 187, Cr 73) Open Cluster in Orion

Located at: RA 05 hours 35 minutes 12 seconds, Dec -04 degrees 26 minutes 00 seconds

Size: 24' (28') Magnitude: 4.2 Class: III 3 p n

North is up

West to the right

Telescope:

 8" f5 Newtonian reflector

Camera:

  ST-8XME, self-guided, binned 1x1, temp -25c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 240 minutes  (24 x 10 minute subs) 02/22/2010; seeing 2.6-3.8 FWHM per CCDStack

Processing:

CCDStack 1.6.1, Photoshop 7.0

Location:

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

Notes:

This sparse open cluster is located just north (above) NGC 1973/1975/1977 (aka "Running Man Nebula"), which is the nebulosity to the south (below), and M 42 / M 43.

According to "Star Clusters", by Brent Archinal and Steven Hynes, the size of this open cluster is 28 arc minutes.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 1981

NGC 1981 = Cr 73 = OCL-525 = Lund 187
05 35 10 -04 25.5
V = 4.6;  Size 25

8": bright cluster with about two dozen stars mag 6 and fainter.  Very large, 
scattered.  Includes ?750 = 6.0-8.0 at 40".  To the south is another group of 
bright stars surrounded by the emission nebula N1973-N1977.

- by Steve Gottlieb