Astron. Astrophys. Suppl. Ser. 132, 83-92

The intraday variability in the radio-selected and X-ray-selected BL Lacertae objects

J.M. Bai¹ - G.Z. Xie^1,2 - K.H. Li¹ - X. Zhang^1,3 - W.W. Liu¹

Send offprint request: J.M. Bai

1 - Yunnan Astronomical Observatory, The Chinese Academy of Sciences, Kunming 650011, China
e-mail: gzxie@public.km.yn.cn
2 - United Laboratory of Optical Astronomy, The Chinese Academy of Sciences (ULOAC), China
3 - Department of physics of Yunnan Normal University, Kunming, China

Received September 27, 1997; accepted April 15, 1998

Abstract:

Seven BL Lac objects have been photometrically observed in an effort to study the difference of optical intraday variability between the radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs). The objects we observed are selected arbitrarily. They are four RBLs, PKS 0735+178, PKS 0754+101, OJ 287 and BL Lac, and three XBLs, H 0323+022, H 0548-322 and H 2154-304. During the observation all of them exhibited microvariation, and H 0323+022 and H 0548-322 sometimes showed brightness oscillation. PKS 0735+178 and BL Lac were in their faint states and not very active. It seems that RBLs do not show microvariability more frequently than XBLs.

Key words: BL Lacertae objects: general -- galaxies: photometry