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Astron. Astrophys. Suppl. Ser. 144, 481-485

Optical observations of five X-ray selected BL Lacertae objects[*]

M. Villata1 - C.M. Raiteri1 - M.D. Popescu2 - G. Sobrito1,3 - G. De Francesco1 - L. Lanteri1 - L. Ostorero3

Send offprint request: M. Villata

Correspondence to:

1 - Osservatorio Astronomico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese, Italy
2 - Astronomical Institute of the Romanian Academy, St. Cutitul de Argint 5, 75212 Bucharest 28, Romania
3 - Dipartimento di Fisica Generale, Università di Torino, Via P. Giuria 1, I-10125 Torino, Italy

Received February 15; accepted April 11, 2000


We present optical data obtained with the 1.05 m telescope of the Torino Astronomical Observatory for five X-ray selected BL Lacertae objects. The data are in the Johnson's B, V, and Cousins' R bands. As the observing periods include the pointings of the Satellite per Astronomia X "Beppo'' (BeppoSAX), our optical information will be comparable with the X-ray observations for a better understanding of the properties of these objects. The present data also provide optical information on sources that have been rarely observed in the optical band. Variability on short time scales (a few days) was found only for 1ES 1959+650.

Key words: BL Lacertae objects: general -- BL Lacertae objects: individual: 1ES 0145+138, 1ES 0323+022, 1ES 1028+511, 1ES 1118+424, 1ES 1959+650

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