NGC 869  Double Cluster                        Click on photo to return to 'Open Clusters and Star fields'                                                    Home               
 
NGC 869    Double Cluster in Perseus

Other description: Open cluster dense.
Constellation:  Perseus
Dreyer description: Remarkable! Cluster, very, very large, very rich in stars, stars of magnitude 7 to 14.
Magnitude:  4.0
RA: 02h 19m 00.0s  Dec: +57°09'00"  (Epoch 2000)
Always above horizon.  Transit: 05:56
Size:30.0'

SEDS description
h Persei, NGC 869
chi Persei, NGC 884

Right Ascension
2 : 19.0 (h:m)
2 : 22.4 (h:m)

Declination
+57 : 09 (deg:m)
+57 : 07 (deg:m)

Distance
7.1 (kly)
7.4 (kly)

Visual Brightness
4.3 (mag)
4.4 (mag)

Apparent Dimension
30 (arc min)
30 (arc min)

Perhaps known pre-historically. Cataloged 130 B.C. by Hipparcos. The famous double cluster in Perseus was known in antique times (probably even pre-historically), and first cataloged by the Greek astronomer Hipparcos. Both clusters are situated in the Perseus OB 1 association, and also only a few hundred light-years appart, at a distance of over 7000 light years. They are both quite young: h is listed at 5.6, chi at 3.2 million years (Sky Catalog 2000); their hottest main sequence stars are of spectral type B0. They are approaching us at 22 (h) and 21 (chi) km/sec, respectively.

O'Meara and Green (2003) point out to some historical confusion about the identity of the designations or names, or the objects "Chi" and "h" Persei. As they point out, since the 1840s, the name "Chi" is attributed to NGC 884, and "h" to NGC 869. However, these authors point out that very probably, Tycho Brahe measured one position for the "nebulous star" that is actually the double cluster, and Johann Bayer designated this "star" as Chi. Probably, he used the name "h Persei" for a fainter nearby star.


Photo Specifications:

      TELESCOPE:  80 mm Celestron APO  F/8
            CAMERA:  'SBIG' ST-8XE & CFW8 color filter wheel
CAMERA TEMP:  Temp. = -20 C
                   DATE:  2/7/08

Filter
Total
Exposure  time
Sub-frame
 Exposure time
Number  of Sub-frames
Binning
Luminance
Red
12 min
120 sec
6
1x1
Green
12 min
120sec
6
1x1
Blue
16 min
120 sec
8
1x1
Other









Processing:    MaxIm; calibrate,  DeBloom, color combine, CCDstack align,  Photoshop CS2