The second object to be studied under the outburst monitoring program was the symbiotic system YY Herculis. The observing campaign for YY Her was much less extensive than the Z And comapaign, as the YY Her outburst was much smaller and of shorter duration. Our coverage consisted of UBVR light curves from the Katzman Automatic Imaging Telescope (KAIT), shown in the top panels of both plots below, optical spectra from the FAST spectrograph on the 60-inch telescope at Mt. Hamilton, and several radio observations with the very large array (VLA; bottom panel on the right).
The magnitude scale for the differential KAIT light curves is arbitrary. Note that the U-B color was almost constant as the outburst decayed. Contrast this behavior to that of AG Dra, in which the U-B color became much redder as the outburst declined.