Wednesday, July 28, 2021

imaged gamma Her at 1 sec (Halifax)

Noting an empty queue at the burke-Gaffney Observatory, due to the bright Moon, I submitted a job for γ (gamma) Herculis aka SHJ 227. I have visited this double star system many times. Noted it. Sketched it. And I have imaged it with the BGO. But the D companion eludes me.

So, had another go, but a much longer exposure, compared to previous. 16 and 27 Aug' 19 were at a tenth of a second. Also tried a ½ second. Doubled.

double gamma Herculis in luminance

Luminance only, 1 second subexposures, 12 stacked shots. FITS Liberator, GIMP. North is up; east is left.

I like all the field stars.

OK. 

B is easy. Down and right. That's south-west.

C is visible. Obvious when zoomed in. Nearly due west. Just above the diffraction spike. Oh... it has some very faint neighbours.

Mystery star that I spotted visually way back in August 2019 is here. In fact, it's brighter than C! A variable star? This is definitely not shown in SkyTools.

GSC 01513-0543, as seen before, is inline with but well beyond B.

I believe there's an artefact in this image, a stacking issue, that's creating the bright bump on the east diffraction spike.

There are mag 15 and 16 stars in this image.

And D? If the WDS is right, D should be south of A, close, at mag 8.

DRS 58 AD at 176°, 8.3", mag 8.1, a blue-white A-class star.

It'd be in the glare of A...

There are double diffraction spikes...

§

Still don't know what the mystery star is but it's not my imagination. Saw it in an RC 16", sketched it in September 2019 with a C8" at high power, and I've tagged it easily in this image.

Still can't spot the D star. The typical double star challenge of a bright primary, a secondary at delta mag 3 or 4, in close.

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