[vsnet-alert 6862] Re: [vsnet-campaign-dn 1833] TK4 : was there an outburst ?

[aah@nofs.navy.mil]

I had a few hours back in Flagstaff to read email and take care
of a few matters before my next trip.  I did the astrometry/photometry
on the TK4 quiescent images that were taken with the
1.0m on 011018UT (HJD 2455200.616).  The
results are as follows, for the close north/south pair:

           RA (J2000) DEC          V    B-V   verr   bverr
North  19:13:58.40  +40:44:12.3  20.84  1.56  0.057  0.179
South  19:13:58.42  +40:44:09.2  21.26  0.18  0.102  0.125

The astrometric error is about 100mas.  Obviously, the
southern star both matches the position given in IBVS 5058
(19:13:58.47  +40:44:09.1 J2000) and is a blue star.
Beware of the northern companion as it will appear a couple of
magnitudes brighter for those observing unfiltered.  I think the
USNO-A position of the northern red companion has been compromised
by the light from TK4 and so is unreliable; there is no evidence
of proper motion for either star.

I have also placed a revised finding chart on the ftp server:
http://ftp.nofs.navy.mil/pub/outgoing/aah/temp/tk4v.jpg
(this is a 3.4x3.4 arcmin field, Vband, pretty deep)

Note that both a single-night field photometry file and
Bruce Sumner's sequence for this field also reside there:
http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/tk4.dat
http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/sumner/tk4.seq

As to whether an outburst was seen, the observers will have to
tell us which star(s) they were actually observing.
Arne

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