Open AccessOptical R ‐band variability of seven X‐ray‐selected BL Lacertae objects
Author(s) -
Kapanadze Bidzina Z.
Publication year - 2009
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2009.14976.x
Subject(s) - physics , astrophysics , bl lac object , brightness , blazar , amplitude , light curve , photometry (optics) , observatory , telescope , astronomy , gamma ray , stars , optics
This paper presents the results of optical CCD photometry in the Cousins R band for seven X‐ray‐selected BL Lacertae objects. Observations have been performed with the 70‐cm meniscus telescope of Abastumani Astrophysical Observatory, Georgia. The data obtained provide important information on sources that have been rarely observed in the optical band. The targets show clear long‐term variability with time‐scales of 1.5–5 yr. The maximum amplitudes are slightly greater than 1 mag. 1ES 0323+022, 0502+675 and 0806+524 show clear non‐periodical behaviour. 1ES 1028+511 changes quasi‐periodically but further monitoring for periodicity confirmation and period derivation is needed. Overall brightness variation is maximal for 1ES 0647+250 with Δ R = 1.29 mag. Two‐peak maxima, indicating the existence of reverse shocks in blazar jets, are observed for 1ES 0502+675, 0647+250, 0806+524 and 1517+656. The targets do not show intra‐night variability. Day‐to‐day changes with amplitudes of 0.1–0.32 mag coincide mainly with short‐term bursts. The latter are seen at faint (quiet) stages as during flaring activities. This fact leads to the suggestion that both hot‐spot and shock‐in‐jet models explaining the origin of short‐term bursts should be reasonable.