Variable Stars - U Gem
Type SS Cygni, Eclipsing binary Click for lightcurve  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: March 1, 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.
Hills Observatory: 1 January 2013 to 6 May 2018
COMETS COMETS
DEEP SKY DEEP SKY