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.


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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