Photometric and spectroscopic observations of the outburst of the   symbiotic star AG Draconis between March and June 2016
  The symbiotic star AG Dra experienced a double-peaked outburst of 0.6 magnitudes in April and May 2016. Photometry and spectroscopy through the outburst showed the B-V colour index varying linearly with the V magnitude and enabled the temperature variation of the hot star to be calculated from the changing flux in the H beta and He II 4686A emission lines. 
David Boyd
astro-ph.SR