TypeZ AndClick for lightcurveSymbiotic variables of the Z Andromedae typeare close binaries consisting of a hot star, a star of late type, and an extended envelope excited by the hot star's radiation. The combined brightness displays irregular variations with amplitudes up to 4 mag. in V. A very inhomogeneous group of objects. AAVSO Alert #572: 3 April 2017Dr. Rudolf Gális (Pavel Jozef Šafárik University (Slovakia)) and colleagues have requested AAVSO assistance in observing the symbiotic variable AG Dra. Observations are requested as a follow-up to spectroscopic observations and in order to monitor the system for an anticipated outburst.Dr. Gális writes: "AG Dra is one of the best studied symbiotic systems, which undergoes characteristic symbiotic activity with alternating quiescent and active stages. The latter ones consist of several outbursts in intervals of about 1 yr. After seven years of flat quiescence following the 2006-08 major outbursts, in the spring of 2015, AG Dra...[entered the active stage]...with...two minor outbursts (in 2015 and 2016) up to now. Such behaviour is quite unusual in the photometric history of AG Dra, so the further systematic photometric monitoring of this symbiotic binary is highly desirable. We expect the next outburst of AG Dra in the late spring of 2017..."Daily monitoring of AG Dra (V~7.9-10.3) in UBV(RI) filters is requested beginning at once and continuing until further notice. When the outburst occurs, revised observing instructions will likely be issued via an AAVSO Special Notice.
Hills Observatory: 1 January 2013 to 8 October 2018