Friday, July 14, 2017

imaged HR 8 (Halifax)

BGO imaged HR 8, aka STT 549, a multi-star system in Andromeda. Centred on GSC 01735 00996.

multi-star system HR 8 in luminance

Luminance only, 4 seconds subexposures, 20 stacked shots. FITS Liberator, GIMP. North is up; east is left.

Back in Sep '16 I had viewed this system but had not seen the C star. The photo is very interesting. Clearly, to the south-south-west, there is a double. This is the C and D pair. The curious thing is that the position of the D star is very different from the SkyTools software. The software chart shows C and D well separated and D almost due west of C; the photograph gives the impression they are on top of one another. Looks like D is moving fast to the east.

This seems to support the data in the WDS.

Now the strange thing with this multi-star system is the E star. I learned of the fifth element via the Washington Double Star database. But it does not appear in the photo even though I can see magnitude 17 stars. LAF 21 (AE) should be opposite B.

annotated photograph of HR 8 A, B, C, and D

I don't see anything...


Using Triangle Calculator, I computed the D star with a:
  • theta (PA) of 200 + 0.213° which I rounded to 201
  • rho (sep) of 144.954" which I rounded to 145.0
So, the good news is that I finally spotted the D star.

The bad news is that I can't find the E. But then, I'm suspicious of the single entry from LAF.


Halved the exposure time on 1 Sep.

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