The QSO 1156+295 - A multifrequency study of recent activity

Photometric observations are presented for outbursts of the quasi-stellar object QSO 1156+295 in 1981 and 1982. High time resolution photometry is included showing variations on time scales of weeks to about half an hour. Data from early plate material show that the object may have been quite bright at the beginning of this century but was quite faint and probably inactive between about 1950 and the beginning of recent activity in 1977-1979. Some results of optical linear polarization are discussed. In examining spectrophotometric results, broadband spectra show very little change in spectral shape during changes in continuum brightness. High resolution spectra (0.1-A FWHM) show no evidence for the Mg II 2798-A absorption sometimes seen in optically violent variables and other QSOs. The radio flux density variations at several frequencies are documented and discussed and compared with the optical light curve. Models for 1156+295 are discussed including variability time scales, and the observed energy output is compared with a magnetic accretion disk model proposed by Shields and Wheeler (1976). Results are summarized and the different sizes of active and inactive regions of the object are compared.