Wednesday, September 16, 2020

looking for BAL 1588

I found a "neglected" double star in the Washington Double Star database with only one observation from 1909. BAL 1588 in Aquarius. It is marked with "X" in the notes, the symbol for a "dubious double."

On checking SkyTools 3 Pro, I did not find a corresponding entry. But, using the location data (212509.61+015616.6), I identified GSC 00533-0360 at the same spot.

So I sent BGO Robotic Telescope on a mission.

area near double star BAL 1588

Luminance filter, 2 second subexposures, 12 stacked shots. FITS Liberator, GIMP. North is up; left is east.

A good image despite sketchy conditions (some cloud, below average transparency, poor seeing).

GSC0053300360 is the medium-bright star up and left of centre. 

I do not see an obvious double near the centre of the image.

The WDS record says the position angle is 134 and the separation is 17.2. The star magnitudes are listed as 11.1 and 12.8.

ST3P reports GSC 00533-0360 as mag 11.8 (though poor quality).

The bright star to the right or west is HD 203873. To the right of that, nearly due west, in the dimmer star GSC 00533-0394, which is mag 12.8. That's way too far away...

The dim star to the south-east of GSC 00533-0360, a good distance away, is GSC 00533-0799. It's suspect datum for the magnitude is 13.3. It's nearly on the position angle. But again, not applicable by brightness and distance. 

So, this one remains a mystery...

It's fun that double star HD 203993 aka A 2289 is in the frame, to the north-east. ST3P says, in fact, it is a triple with AB separated by 0.2 seconds of arc. No. So we're seeing the C companion, around 225°. The planning app says they are magnitiudes 7.5 and 11.3 and 15.4" apart. Nice appearance. 

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