  The BTr and UBr satellites observed $\beta$ Lyrae from May to October 2016 to
continuously monitor light-curve instabilities with the time resolution of
about 100 mins. An instrumental problem affecting localized patches on the BTr
CCD detector has been discovered by comparison with partly simultaneous UBr
observations; the origin of the problem is being investigated. A zero-point
offset permits utilization of the BTr data for a time-series characterization
of deviations from the mean light curve defined to $\simeq 0.0025$ mag.
