Limiting magnitude for the Harvard plates inspected in the search for past bright episodes of the program stars. For V2492 Cyg and ASASSN-15qi, we have plotted the B-band magnitude of the faintest APASS star visible at the microscope in the immediate surroundings of the targets. For V350 Cep we plot the limiting magnitude as derived by DASCH as part of the calibrations of the plate scans.