Thursday, August 25, 2016

photographed NGC 884 (Halifax)

The BGO robot imaged χ (chi) Persei or NGC 884 for me. The other half of the Double Cluster between Cassiopeia and Perseus. The pair of clusters is also called Caldwell 14. One of the RASC Finest NGCs.

RASC Finest open cluster NGC 884 luminance

Luminance only, 60 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; left is east.


Very near the centre of the open cluster, SkyTools notes a double: SAO 23245 aka WFC 8. The software says the partner star is V619 Per, a variable. The positions of the stars in the software closely match my image. But there's something odd. In the Object Information box, A is noted with a magnitude of 9.4 while B is 9.5. The chart however makes B appear brighter. And when I hover over the stars, A shows as 9.4 and B as 6.6! When I specifically double-click on B and examine the Object Information, V619 is listed as a variable star ranging from V 6.59 to V 6.63. And in my image, the "B" star appears dimmer by a magnitude or two from A... That's confusing.

Near the top-left of the image, north-east from the centre of the cluster is a faint double, STI 1857. The dimmer companion is toward the cluster. Curiously, opposite B, is a star of similar brightness, similar separation, making a pleasing visible triple. But it is an unrelated star.

The other half of the Double Cluster is NGC 869.


Wikipedia link: NGC 884.

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