Name of the Speaker(s): Enrico MASSARO
Institution: Istituto Astronomico, Universita' La Sapienza, via G. M. Lancisi 29, I-00161 ROMA (Italy)
Title of the communication: Secular luminosity trends of BLLac objects: the case of OQ 530 (1418+546).
E. Massaro, T. Aniello, M. Maesano, F. Montagni, R. Nesci
Preliminary abstract (12 lines max.): We present an update of the early historical light curve of OQ 530 based on literature and new photometric data. These measurements confirm the decreasing trend of the source luminosity, which has reached in spring 1996 B values around 16.5, about 1 - 1.5 mag brighter than the setimated host galaxy value. The average decreasing rate, over a 90 year interval, is 0.04 mag/year, but i could be even greater (up to 0.08 mag/year) in the last 25 years. Variations on much shorter time scales (weeks to months) with an overall amplitude of about 3 mag are evident in the first part of the light curve but in the more recent data this amplitude could be reduced to about 2 mag. Some considerations on the physical mecahnisms responsible for this long term behaviour are discussed.