BVRI photometry of BL Lacertae in 1993-1995
Abstract
The results of optical photometry of BL Lac over a time interval of two years in the B, V, R, I filters are presented. The source is found for most of the time in a low state. The mean colour indexes are similar to those observed in higher luminosity states, however a flattening of the spectral slope was present during three small amplitude outbursts. A brief comparison with the observations available in the literature and some considerations on the physical conditions driving the appearance of emission lines are made.
- Publication:
-
Astronomy and Astrophysics Supplement Series
- Pub Date:
- April 1997
- DOI:
- 10.1051/aas:1997101
- Bibcode:
- 1997A&AS..122..267M
- Keywords:
-
- BL LACERTAE OBJECTS: GENERAL;
- BL LACERTAE: INDIVIDUAL: BL LAC