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AAVSO 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: matthewt@aavso.org, 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

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: http://www.astro.virginia.edu/xrb_jets

Please promptly report all observations to the AAVSO using the name

This AAVSO Special Notice was prepared by Dr. Matthew Templeton.


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