Optical observations of eight X-ray selected BL Lacertae objects^*

¹ Osservatorio Astronomico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese, Italy
² Istituto di Fisica Generale dell'Università di Torino, via P. Giuria 1, I-10125 Torino, Italy

Send offprint request to: C.M. Raiteri

Received: 23 February 1998
Accepted: 6 May 1998

Abstract

We present optical data in the Johnson's BV and Cousins' R bands for eight X-ray selected BL Lacertae objects (BL Lacs) that have recently been pointed by the Satellite per Astronomia X "Beppo" (BeppoSAX). The observations were done with the telescope of the Torino Astronomical Observatory and the observational periods include, or are close to, the satellite pointings. These data provide optical information on sources that have been rarely observed in the optical band. Moreover, they can be compared to the X-ray ones for a better understanding of the emission properties of these objects. Variability on short time scales (a few days) was found for MS 0317.0+1834, 1ES 0347-121, and MS 0737.9+7441.