Sunday, May 15, 2016

captured NGC 6633 (Halifax)

Wasn't expecting anything tonight but the BGO robot imaged the open cluster NGC 6633 for me. In Ophiuchus, right at the edge of the Serpens Cauda border. One of the RASC Finest NGCs. Looks like there's some trailing in this image.

RASC Finest open cluster NGC 6633 luminance

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

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There's trailing in the other frames! Particularly bad in the green. Damn.

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There are a number of double stars in this open cluster but most are too tight to resolve, like HD 170114 at 1.0 seconds of arc. The focus and tracking issues aren't helping.

GCB 31 is interesting, just at the right edge of the frame, 2/3rds of the way down. SkyTools reports this pair as magnitudes 12 and 10 (i.e. the primary being dimmer) with a separation of 4.50" (in 1946). ST3P says the position angle is (or was) 60°. In the image, it looks more like 75. I wonder if this is a binary.

Finally, there's a wide double in the middle of the Cassiopeia-like W shape on the right centre. SAO 123480, aka SCJ 17. The bright light orange star is the primary. North (up) and slightly right is a fairly bright white star. That's the companion.

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Processed in full colour.

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