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AAVSO Special Notice #29

Observations requested of 2001+32 V550 Cyg
(January 18, 2007)

Coordinates of V550 Cyg: RA = 20:05:05.2  Dec = +32:21:22  (2000.0)

Dr. Jeno Sokoloski, Columbia University, has requested our assistance in
obtaining observations of the SU UMa-type cataclysmic variable V550 Cyg
tonight and over the next few nights. She wants to learn whether the star is
in outburst or quiescence so she may correlate ROSAT observations that were
taken a few days ago. The most recent data we have received (below) show the
star in quiescence; if anyone has more recent observations we encourage you
to upload them to the AAVSO website so Dr. Sokoloski may use them.

Data on V550 Cyg recently submitted to the AAVSO include:
2006 OCT 21.8620 UT, <15.2, G. Poyner, Birmingham, England;
24.9000, <15.0, Poyner;
31.9280, <15.0, Poyner;
NOV 01.8770,<15.0, Poyner;
08.9510,<14.6, Poyner;
09.8610, <15.0, Poyner;
17.9040, <15.0, Poyner;
18.0167, <16.1, D. Taylor, Essex, Ontario, Canada;
23.0215, <15.5, Taylor;
25.8300, <15.2, Poyner;
DEC 08.7830, <15.0, Poyner;
09.8520, <15.0, Poyner;
16.7880, <15.0, Poyner;
2007 JAN 10.7590, <15.0, Poyner;
14.7490, <14.6, Poyner.

According to the AAVSO International Database, the last outburst of V550 Cyg
occurred in June 2006, when the star reached visual magnitude 14.5 and was
magnitude 15.3 or brighter for 5 days. A similar outburst was reported in
August 2000, the star reaching 14.3. At minimum V550 Cyg is fainter than V
magnitude 17.0.

Please observe V550 Cyg visually or using a V filter, and report your
observations to the AAVSO whether you find the star in outburst or quiescence.
Be sure to indicate which chart and comparison stars you used. Long series of
observations are not necessary if the star is at minimum; the goal is to
determine the state of the system. If you find the star in outburst, please
follow it through the outburst (CCD time series runs (V and other filters) with
a cadence such that each observation has at least S/N=50) and after its return
to minimum.

Report observations to the AAVSO as: 2001+32  V550 CYG

AAVSO 'e' and 'f' charts, with sequence by Bruce Sumner and CCDV photometry
by Arne Henden, may be found at:

http://www.aavso.org/cgi-bin/searchcharts3.pl?name=v550%20cyg

Thank you for your astronomical efforts and contributions!

This special notice was compiled by: Elizabeth O. Waagen
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