- NGC 752
NGC 752 is a large open cluster lying along the eastern edge of the constellation Andromeda. It contains around 60 member stars contained within an area approximately 45 arc-min across. This cluster is relatively old (around 1.1 billion years), so it does not contain the blue-white giant stars typical of younger open clusters. It lies at a distance of around 1300 LY. With an apparent magnitude of 5.7, it lies on the edge of naked-eye visibility, although its large size tends to reduce its surface brightness. It is best viewed in binoculars or a small telescope.
NGC 752 was discovered by Caroline Herschel in 1783 and cataloged by her brother William Herschel in 1786. It is possible, however, that this cluster may have been observed by Giovanni Batitsta Hodierna before 1654.
The most conspicuous member of the cluster is the magnitude 7.26 TYC 2816-111-1, which is the yellow star near the center of my image. Most of the other cluster stars have magnitudes ranging from 8 to 12. The triangle of bright yellowish stars in the lower right quadrant of my image are not physical members of the cluster. The close pair of stars in this triangle represents the optical double 56 Andromedae. They have visual magnitudes of 5.69 and 5.89 and lie at distances of 316 and 932 LY. The third member of the triangle is HD 11624, a magnitude 6.28 spectral class K star lying at a distance of 535 LY.
This mosaiced image of NGC 752 was created from 5 images— one of the center of the cluster and the other four forming the corners around it. Each of the five images was created from 16 90-second exposures. This mosaicing was necessay because the cluster is too large to be adequately captured in a single image using the current SOCO system.
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