The Hamburg Quasar Monitoring Program (HQM) at Calar Alto III. Lightcurves of optically violent variable sources

Abstract

HQM is an optical broad-band photometric monitoring program carried out since September 1988. We use a CCD camera at the MPIA 1.2$\,$m telescope. Fully automatic photometric reduction relative to stars in the frames is done within a few minutes after each exposure, thus interesting brightness changes can be followed in detail. The typical photometric error is 1--2\,\% for a 17.5\,mag quasar. We here present lightcurves of 14 known violently variable sources and compare them with literature data. For two BL\,Lac objects, 1E\,1229+645 and 4C\,56.27 (1823+568), this paper is the first variability study. We have also carried out POSS photometry to obtain indications for variability on a longer timescale.