NGC 869 and NGC 884 (Lund 73, Cr 24 and Lund 76, Cr 25) aka "The Double Cluster"

Open Clusters in Perseus

Center of field located at approximately: RA 02 hours 22 minutes 19 seconds, Dec +57 degrees 08 minutes 00 seconds

Size: 29' (18') and 29' (18') Magnitude: 5.3 and 6.1 Class: I 3 r and I 3 r

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:

Red (Hoya 25A) filter, 140 minutes (14 x 10 minute subs), 11/19/2006

Processing:

CCDStack 1.1, Photoshop 7.0

Location:

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

Notes: These two magnificent open clusters are visible to the unaided eye at a dark sky site. Because of their collective sizes, I tried to frame the centers of the clusters in my field, but their member stars spill out of my field of view (about 31' x 46').

According to "Star Clusters", by Brent Archinal and Steven Hynes, the sizes of these two open clusters are 18 arc minutes.

NGC 869 (NGC 869 image separately) is to the West (right), NGC 884 (NGC 884 imaged separately) to the East (left).

From the NGC / IC Project:

Contemporary Visual Observation(s) ...
NGC 0869 = h Per = Cr 24 = Double Cluster
02 19 04 +57 08.1
V = 3.5;  Size 30

17.5": this is the brighter and richer western member of the famous "double 
cluster". Includes a mag 6.6 star near the center and a mag 6.7 star 2.5' NNE.  
Close following the mag 6.6 star is a neat parabolic group of five stars opening 
towards the star.  On the W side of this star is a rich group of ~20 stars 
mostly arranged in an incomplete ring.  A faint curving string of stars from the 
mag 6.7 star leads to the parabolic quintet.  The 20' field at 220x has too many 
stars to count, but probably has ~200 stars.

8": this is the western component of the "double cluster".  Very bright, large, 
about 30' diameter.  Very rich with about 100 stars resolved, includes several 
bright mag 6.5-7.0 stars in the center.  Forms a pair with N884 at edge of 100x 
field.

- by Steve Gottlieb
NGC 0884 = Chi Per = Cr 25 = Double cluster
02 22 32 +57 08.6
V = 3.6;  Size 30

17.5": the following group of the remarkable field of the "double cluster" is 
not as large or bright as N869, but is centered around two wide triple stars.  
The central 5' has up to 50 stars including a number of faint mag 14-15 stars 
forming a rich background.  Off the W end of the central region is a long string 
of stars which heads NE for 10' towards 3 brighter stars and then turning S and 
heading back past a mag 8 orange-red RS Persei.  The 20' field includes ~200 
stars, although the field does include as many bright stars or as compressed as 
N869.

8": this is the eastern component of the "double cluster".  Very bright, large, 
very rich, ~20' diameter, ~60 stars, includes bright colored stars, many 
doubles.

- by Steve Gottlieb