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:

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

2016 link: https://www.aavso.org/vsp

Thank you for your astronomical efforts and contributions!

This special notice was compiled by: Elizabeth O. Waagen


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