Telescope Reviews:

Poster:

cildarith (see all of this user's photos)

Description:

Object Name: NGC 381
Also Known As: H.VIII.64, Cr 10, Lund 38, OCl 317, C0105+613, [KPR2004b] 14
Object Type: Open Cluster
Constellation: Cassiopeia
Right Ascension (2000.0): 01h 08m 19.9S
Declination (2000.0): +61° 35' 02"
Magnitude: 9.3P
Diameter: 7.0'
Trumpler Type: III 1 m
Distance: 3,000 light years
Discovery: Caroline Herschel, 1783 (4.2" reflector)
NGC Description: Cl, pC

Telescope: Parks Astrolight EQ6 • 6" f/6 Newtonian Reflector
Eyepiece/Magnification: 7.5mm Parks Gold Series Plössl • 120x • 26' FoV
Date/Time: 16 November 2009 • 04:45-05:15 UT
Observing Location: Oakzanita Springs, San Diego Co., CA
Transparency: NELM 6.4, TLM 14.2
Seeing: Pickering 7-8
Conditions: Clear, cold, dry, some wind

NGC 381 consists of two roughly concentric circles of faint stars located about 1.6° NNE of Gamma Cassiopeiae. At low magnifications it appears as a condensed knot in the rich field of the Milky Way. The brightest star in the cluster shines feebly at magnitude 11 near the northern edge of the inner ring (the remaining stars – I count about 3 dozen – are 13th magnitude and fainter). This star is also cataloged as the double star Struve I (1st Supplement) 185 (11.2, 12.9; 8.6"; 122°); the companion star is visible at 120x. NGC 381 is superimposed on a faintly glittering veil of unresolved stars particularly in the southeastern half of the cluster. Like NGC 225, Caroline Herschel discovered this cluster (in 1783).

The brightest field star is 8th magnitude HD 6755 near the eastern edge of the high magnification field. Eight minutes of arc to the southeast is a 10th magnitude bluish star that forms a triangle with NGC 381 and HD 6755. This is the Algol-type eclipsing binary OX Cassiopeiae, which has a period of about 2½ days and varies from magnitude 9.9-10.35. Several studies have been done (with conflicting results) to determine whether OX is a member of NGC 381. The most recent results point to similar distances for both cluster and variable.