[vsnet-newvar 1484] Re: Probable new faint variable star in Scorpius

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

From: "Mati Morel" <morel@ozemail.com.au>
Date: Wed, 19 Jun 2002 12:51:10 +1000
Subject: [vsnet-chat 5355] Re:  Probable new faint variable star in Scorpius


----- Original Message -----
From: <aah@nofs.navy.mil>
To: <aavso-discussion@informer2.cis.McMaster.CA>
Sent: Wednesday, June 19, 2002 5:30 AM
Subject: Re: [AAVSO-DIS] Probable new faint variable star in Scorpius


> Mati Morel asked, regarding a possible variable:
> >Is it this apparent variation real?  Or have the A2.0 and GSC2.2 scans
been
> >fooled by the presence of close companions?
>   I am pretty sure both cataloging efforts were fooled by
> the close companions.  I took a BVRI set last night, and there
> is nothing unusual about any of the stars in the arc.  Objects
> that are close enough to 'touch', though, will often feed through
> automatic star detection algorithms.  For example, your arc
> of stars appears in my automated reductions as the single detection
>        RA(J2000) DEC          V     B-V    V-R    R-I
>    16:51:41.75  -29:41:58.9 17.026  0.973 0.634  0.555
> This is a very dense field and I bet if you look around, you will
> find other examples of such mergers.
>   However, the star you chose for EF Sco is in my dataset at
>        RA(J2000) DEC          V     B-V    V-R    R-I
>    16:51:40.35  -29:41:25.5 13.704  1.960  1.213  1.181
> This works out to a Bmag of 15.7, which seems out of the
> 13.3-14.4p range you quote.  I'll get another dataset and
> see if we can identify the variable by its variation.

OOPS!  Thanks Arne.  I  thought EF Sco would be relatively easy to identify,
being one of the brighter variables.
Obviously one has to be careful here, as well.  A very red star like this
one cannot be a RR Lyr star. Another nearby candidate might be one at
16h51m45.08s  -29 41'18.4",  b = 14.7.
        Nikolai Samus of the GCVS team has contacted me; they are working
through the same list of variables, and meeting the same problems in
identifying them.  Martha Hazen has provided assistance by locating the
original workbooks and field sketches at Harvard.. Priority is being given
to variables in Ophiuchus, for volume II of the GCVS;  Scorpius is of lower
priority.  This appears to be the only certain way of identifying many
variables in this busy star field.

Regards,
Mati

morel@ozemail.com.au

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