Telescope:

 8" f5 Newtonian reflector

Camera:

  ST-8XME, self-guided, binned 1x1, temp -25c, camera control MaxIm DL5.46

Image:

Lumicon Red filter, 180 minutes (18 x 10 minute subs), 12/19/2008; seeing 2.3-3.0 FWHM per CCDStack

Processing:

CCDStack 1.4.1, Photoshop 7.0

Location:

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

Notes:

This image replaces a red filtered 90 minute Track & Accumulate image from 02/13/2006.

According to "Star Clusters", by Brent Archinal and Steven Hynes, the size of this open cluster is 20 arc minutes.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 1817

NGC 1817 = Cr 60 = OCL-463 = Lund 156
05 12 26 +16 41.1
V = 7.7;  Size 16

17.5": large, roundish group of ~100 stars in a 15' diameter.  The three 
brightest mag 8/9 stars lie on the W side.  This trio is part of a 7' arc of 15 
stars elongated N-S sharply defining the preceding side of the group.  The 
cluster is fairly well detached except at the E side which merges into the 
general field density.  About 5' NW of the trio described above is a mag 8.6 
star (unequal double) but it appears detached from the main group.  25' SW is 
the bright, striking group N1807 which has a cruciform outline.

8": about 65 stars in 15'-20' diameter, large, fairly rich, many faint stars.  
Includes three brighter stars on the W side including a mag 8.5 star.  Forms a 
poor version of the "Double cluster" with N1807 25' SW.

- by Steve Gottlieb