CH Cygni Precipitous Fading

Hi Everyone,

The symbiotic star CH Cyg appears to be undergoing a fading and reddening event with increasing rapidity. The decline amplitudes between April 17 and June 28 2018 as measured from 3 sets of UBV observations made during that time interval appear to be greatest in U (2.0 magnitudes), followed by B (1.6 magnitudes), and finally in V (0.9 magnitudes). The U-B index appears to have decreased from -0.5 to -0.1 during this interval while B-V has increased from +0.5 to +1.2. Looking at observations submitted just in the past few days suggests the rate of fading has increased substantially. Might the hotter, bluer components of this complexed system be undergoing a partial or total eclipse by the semi-regular red giant secondary ? More observations are planned.

Steve