Monday, August 08, 2016

caught NGC 40 (Halifax)

The Burke-Gaffney robotic telescope imaged NGC 40 for me. A very interesting planetary nebula in Cepheus. One of the RASC Finest NGCs. Sometimes called the Bow-Tie Nebula.

RASC Finest planetary nebula NGC 40 luminance

Luminance only, 15 seconds subexposures, 20 stacked shots. FITS Liberator, Paint.NET. North is up; left is east.

There are also a couple of very nice double star systems in the field...

At the 10 o'clock position from the nebula, i.e. east-north-east, ¼ of the way from centre, the bright star... that's the A (and B stars) of SAO 4061. The fairly bright star above and slightly right (north-north-west) of A is the C star. Curiously, SkyTools 3 Pro does not show the tight B star until one dramatically zooms into Interactive Atlas. It shows below or south. ST3P, in the Object Information box, says B is 0.5 arcseconds away. The photo however shows a star dimmer than C below A, slightly right, and rather tight. What star is this?! Part of the system or some other star with high proper motion... The WDS shows the AB theta or position angle was 165 in 1971 and 157 in 1991. That's about 10° in 2 decades. And the rho or separation was 0.4 and then 0.5. So moving away. Another 20+ years have gone by... Both ST3P and the WDS suggest they are the same magnitude. Very curious.

At the bottom-right of the image, so south-west of the planetary, is the fairly tight couple HJ 1940. Bright primary and dimmer secondary to the south-east. Thin black line between them.


Collected Hα and O-III data on 14 Sep '17.


Wikipedia link: NGC 40.

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