2001/07/02 by L. Tommasi, Leonardo Tommasi, E. Palazzi +9
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Pulsars and Gravitational Waves Research #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.1051/0004-6361:20010940
11 pages, 7 figures, accepted to Astronomy & Astrophysics
arxiv created 2001/07/02 · openalex publication_date 2001/09/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
Optical polarization of seven selected BL Lac objects in UBVRI bands was studied with the Nordic Optical Telescope from December 10-14, 1999. Two of them, 3C 66A and PKS 0735+178, were monitored for 4 nights for a total integration time of 4.75 and 5.5 hours, respectively. Other objects (1 Jy 0138-097, H 0414+009, PKS 0823-223, OJ287 and BL Lac) were observed sparsely during the run. Apart from PKS 0823-223 (more polarized than observed in the past), the sources show levels of flux and polarization consistent with results at previous epochs. 3C 66A and PKS 0735+178 were intensively observed during December 11 and 12 and exhibited variability of polarization, both on internight and intranight time scales. Wavelength dependence of polarization has been investigated, as well as circular polarization. The results are discussed within the standard model for BL Lacs.