Wednesday, February 24, 2016

verified double near 59 Ser

Finally got 'round to investigating the neighbourhood around 59 Serpentis.

Closely re-examined the photo captured at 12:47 AM on Saturday 5 July 2014 during the varied session. 59 Ser had found its way onto my SkyTools 3 Pro observing list from the RASC Observer's Handbook, specifically from the Coloured Double Stars table.

I noticed something odd in the photo compared to the charts in the ST3P software. I was seeing what looked like an obvious double star to the south-west of 59 Ser but the software was only showing a single star, GSC 00433-0179, at magnitude 10.9. Due east of this star I was seeing a brighter element.

A year later, at 12:09 AM on Monday 20 July 2015, I had another look. A visual observation this time, to do two things: assess the colours; see if the other double was really there. My perceived colour disagreed with the RASC list but meshed with Haas. The other pair was definitely there.

Tonight I created a multi-layer diagram in Paint.NET. Put my photo at the bottom. Placed a detailed chart from SkyTools on the second layer. Made a third layer for the direction indicator. And finally dropped an image from Aladin.

photograph of double star 59 Ser

My photo. 59 Ser A and B are merged in the overexposure. Mystery star double star, above image centre, is obvious.

screen snapshot from SkyTools of double star 59 Ser

SkyTools 3 Pro with designations (and hand-drawn direction indicator) shown. Mystery double not noted.

photograph from Aladin of double star 59 Ser

Image from Aladin clearly shows mystery double.

So, I dove into the Washington double star database. Verified 59 Ser showed the AB pair. It also lists Aa and Ab. Then I looked in the 'hood. At the coordinates 18269+0009 I found BAL1195. Ah ha!

number of observations:    4
magnitudes:    11.89    12.73

observations:    first;    last
date:    1909    2000
theta (PA) °:    299    296
rho (sep.) ":    8.8    8.8
proper motion RA ":    -2    -5
proper motion Dec ":    -9    -9

precise coord. J2000:    182658.10+000816.3
precise decimals RA:    18h26m58.10s
precise decimals Dec:    00°08'16.3"

That was definitely it. So, it turns out that I imaged and viewed a known double but this pair is not shown (and is not searchable) in SkyTools. A double discovered by R. Baillaud.

Updated my life list accordingly.

Mystery solved.


I also rejigged the doubles life list slightly, moving the 59 Sep entry higher in the list, to correspond to the first "observation" (er, image viewed) a year prior.

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