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Special Notice #204: Request for monitoring of SS Cygni in support of EVLA/VLBA radio observations

April 15, 2010: Dr. James Miller-Jones (NRAO, Charlottesville) requests the assistance of AAVSO observers to provide rapid notification of the next outburst of the dwarf nova SS Cygni. A confirmed detection of an outburst will be used to trigger-radio wavelength observations of SS Cygni using the NRAO's EVLA and VLBA radio telescopes. Radio observations will be used to study jet formation in dwarf novae, and rapid notification of the onset of outburst is needed. This project follows in the footsteps of a previous campaign by Dr. Elmar Koerding to examine the same phenomenon.
SS Cyg is the class prototype of the dwarf novae, and the brightest dwarf nova in our skies. In quiescence, SS Cyg varies around V=12.0, and will typically reach V=8.0 at maximum, although anomalous weak outbursts are sometimes seen. SS Cyg last went into outburst between 2010 March 01 (JD 2455257.3924; T. Bjerkgaard, m(vis) < 11.4) and 2010 March 04 (JD 2455259.6708; J. Spiel, m(vis) = 8.9). The next outburst may occur at any time. Observations brighter than m(vis) = 11.0 should be reported as quickly as possible.
Observers are asked to increase their monitoring of SS Cyg through the third week in May. Please report all observations as soon as is practical. In the event of an outburst, please report your observations as quickly as you can via WebObs, and also notify Dr. Matthew Templeton at AAVSO Headquarters (email:, phone: +1-617-354-0484). Visual magnitude estimates are a fast and effective means of monitoring SS Cyg; CCD observations are also useful, but please reduce your frames and report your data as soon as possible following an observing run. CCD time-series are not specifically required for this project.
SS Cyg is located at the following (J2000) coordinates:
RA: 21:42:42.79 , Dec: +43:35:09.9
Charts for SS Cyg may be plotted using AAVSO VSP:
For more information on this project, please see Dr. Miller-Jones' website:
Please promptly report all observations to the AAVSO using the name "SS CYG".
This AAVSO Special Notice was prepared by Dr. Matthew Templeton.


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