[vsnet-chat 2907] (fwd) On DV Dra identification

[Taichi Kato <tkato>]

(fwd) On DV Dra identification

Date: Sun, 7 May 2000 20:51:36 +0300 (EET DST)
From: stars@personal.eunet.fi (Timo Kinnunen)
Subject: DV Dra id problem

  Hello,

  In the following message Kato-San wrote:

>[vsnet-obs 1605] DV Dra outburst, continuing?
>
>DV Dra
>
>    A 6-min V-band CCD exposure of DV Dra taken at Ouda Station last night
>clearly shows DV Dra (WZ Sge-type candidate) siginificantly brighter than
>in Downes & Shara (1993) chart.  Astrometry using 6 GSC stars (mean residual
>0".3) gives 18h17m24s.44 +50o48'16".6 (J2000.0).  This position is slightly
>different from that given in Downes & Shara (1993), but is in good agreement
>with one (18h17m24s.44 +50o48'16".3) obtained by M. Iida from his outburst
>CCD image (Iida, private communication).  Reanalysis of the Nov. 13 CCD
>image (already reported in vsnet-obs #1595, but the measurement was done
>for the coordinates by Downes & Shara (1993)) confirms this finding.


  The position given above, and also the SIMBAD position:
18 17 25.070 +50 48 14.50 (2000)
fall only a few arcseconds from an A2.0 star 1350.09592107
- at  18 17 24.71  +50 48 19.19  (2000)

  DV Dra can be very easily confused with this star - it is
certainly noteworthy, however I could not find any remarks on it
from 1995 outburst reports. Pardon me, I don't have the relevant
IBVS issue at hand, but I find it interesting that the outburst
photometry apparently was not disturbed by this A2.0 star.


>  Reexamination of POSS and the candidate by Downes &
>Shara (1993) in digitized GSC survey plate would help identifying the nature
>of this intriguing outburst.

  I checked the available POSS scans at USNO Flagstaff -
the following plate shows a DV Dra candidate some 10" due N
from this A2.0 star.
Details:

> POSSII 0229  SJ06278 1995.4976

see 5' square image at

  http://vsnet.nofs.navy.mil/tmp/fchaanCqa_sj0229.000.jpg

I believe the date is close to 1995 June 30 - about four months prior to
the outburst report by Iida, so it would be very intriguing to find out
whether the POSS-II candidate is true DV Dra, another variable,
or a plate flaw.

Regards,
Timo Kinnunen

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