X-Ray and Optical Observations of X-Ray--selected BL Lacertae Objects
Maccagni, D.; Giommi, P.; Garilli, B.; Maccacaro, T.; Barr, P.; Gioia, I. M.; Schild, R. E.
Netherlands, Italy, United States
Abstract
Results from several X-ray and optical observations of five X-ray-selected BL Lacertae objects are reported. X-ray light curves covering periods of up to 6 yr reveal that the X-ray flux from these objects does not show large-amplitude trends over this time scale. Variations of up to 2 mag have been observed in the optical. The soft X-ray spectra of three objects have been measured with the Exosat Medium Energy detectors. Energy spectral indices range between one and two. In one case (1E 1415.6 + 2557), evidence for photoelectric absorption in excess of that due to the local interstellar medium has been found. A new optical flare from 1E 1402.3 + 0416, with rise and decay time of order of a few weeks, has been detected.