U Gem
Type: SS Cygni; Eclipsing binary
AAVSO lightcurve (2020 )
AAVSO lightcurve (index)
SS Cygni-type variables increase in brightness by 2-6 magnitudes in V in 1-2 days and
in several subsequent days return to their original brightnesses. The values of the cycle
are in the range 10 days to several thousand. Eclipsing binary systems are binary
systems with orbital planes so close to the observer's line of sight (the inclination of the
orbital plane to the plane orthogonal to the line of sight is close to 90 deg.) that the
components periodically eclipse each other. Consequently, the observer finds changes
of the apparent combined brightness of the system with the period coincident with that
of the components' orbital motion.
AAVSO Alert 539: 1 March 2016
Ms. Deanne Coppejans (PhD candidate, Radboud University Nijmegen (Netherlands)
and University of Cape Town) and colleagues have requested AAVSO observer
assistance in monitoring several northern dwarf novae in support of their campaign to
observe them with the Very Large Array (VLA) in their ongoing radio jet research. Their
research on radio jets in dwarf novae has been discussed in AAVSO Alert Notice 505
(https://www.aavso.org/aavso-alert-notice-505). Nightly observations are sufficient to
determine whether the source is in outburst or quiescence when a VLA observation is
taken. In this campaign, the VLA observations are not triggered by the PI, so there is no
way to predict when the VLA will observe the sources. Observers will be notified
whenever VLA observations are obtained, but no modification of observing instructions
is expected. Nightly visual or V observations are requested beginning now and
continuing through June 2016.