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Alert Notice 536: SS Cyg monitoring requested for radio campaign

February 8, 2016:  Further to AAVSO Special Notice #412, Dr. James Miller-Jones (International Centre for Radio Astronomy Research, Curtin University, Perth, Western Australia) and colleagues have requested AAVSO assistance in support of their multiwavelength (radio and optical) campaign on the dwarf nova SS Cyg. Close monitoring of SS Cyg and immediate reporting of observations to the AAVSO via WebObs is requested beginning now.

Previous similar campaigns with Dr. James Miller-Jones and his colleagues have been very successful; AAVSO observations were used to trigger multi-site radio observations in research on radio emission from SS Cyg, as well as for correlation with the radio data during analysis (AAVSO Alert Notices 345, 360, and 445).

Dr. Miller-Jones writes: "Dr. James Miller-Jones and an international team are aiming to use the e-MERLIN array of radio telescopes (7 antennas spread across the UK) to observe the next outburst of the dwarf nova SS Cygni. They are aiming to determine whether or not resolved radio jets exist in this system, and will use the high angular resolution and exquisite sensitivity of e-MERLIN to make deep images of SS Cygni during outburst, when any jets, should they exist, would be most likely to be detectable. The outburst will also be tracked with dense monitoring from the Arcminute Microkelvin Imager - Large Array (AMI-LA; a radio telescope based in Cambridge, UK), to provide the most complete radio coverage of an outburst of any dwarf nova system to date. They seek support from the AAVSO both to trigger their radio observations, and also to provide optical coverage of the outburst that can be compared with their radio light curves."

The radio emission in SS Cyg occurs early in the outburst, so it is essential to know when the outburst is beginning in order to trigger the multi-site radio observations. If the outburst cannot be detected early enough, the radio observations will not be triggered, but will be held for a later outburst.

Data in the AAVSO International Database indicate that SS Cyg may go into outburst very soon, so please keep a very close watch. Visual and CCD/DSLR (particularly V) observations are requested (no time series unless outburst is underway and radio observations have been triggered). Its normal minimum magnitude is ~11.8 V, but it can fluctuate to around 11.5. If it becomes brighter than 11.5 V, it could well be going into outburst. If it reaches 11.0, it is almost certainly on its way up.

Once SS Cyg goes into outburst, please continue your observations until SS Cyg has returned to minimum. The radio observations will continue throughout the outburst, so your optical data from the entire outburst will be essential for correlation.

Please use WebObs to report your observations of SS Cyg to the AAVSO as soon after you make them as possible. If you see it 11.5 V or brighter, please report them immediately.

Coordinates: RA 21:42:42.8  Dec. +43:35:10  (2000.0)

AAVSO finder charts for SS Cyg with comparison stars may be generated using the AAVSO Variable Star Plotter (VSP).

Please submit your observations to the AAVSO International Database using the name 'SS CYG'.

This AAVSO Alert Notice was prepared by Elizabeth O. Waagen.

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