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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