Monday, January 09, 2017

NGC 2539 and 19 Pup (Halifax)

Back on 15 Dec, I tried to image the Finest NGC 2539 with the Burke-Gaffney system. The result was satisfactory but the open cluster was not quite centred or framed the way I wanted. So I aimed a bit to the east, centering on TYC 05434-2972 1. It worked. And this time I also caught the multi-star system 19 Pup.

NGC 2539 and 19 Pup in luminance

Luminance only, 30 seconds subexposures, 10 stacked shots. FITS Liberator, Paint.NET. North is up; east is left.

19 Pup aka BU 1064 is to the south-east, near the bottom-left corner of the image. The D and E components, to the west of the primary, are obvious. D is the dimmer star to the north; E is brighter below. Curiously, SkyTools 3 Pro, according to the chart display, says D shines at magnitude 8.9 while E is 9.4. But E is clearly brighter. The Object Information box says E is mag 7.8. That's better.

Now things get really interesting. There's a pair of stars (GSC 05434-3319 and GSC 05434-2503) with similar spacing to D and E to the south of D and E and fainter than D. They are not part of this system. There's J081115.6-125648 to the south of A, about the same separation as E, brighter than D, but again is not considered an element. Why would they not be included with the others when they are as close and bright?

There's something up with the C star. ST3P shows C to the north-west of A at mag 13.2. The photograph shows a star at this position but extraordinarily dim. Is that it? Or did C move?

ST3P shows the A and B stars as very tight (and very different) so I'm not surprised that I cannot isolate them in this image. Too bad there are optical problems in this corner. Doesn't help.

There seems to be a glow around this multi-star system. I'll look in that, check and see if there's something really there.


Did a deeper analysis of 19 Pup.

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