The Ultraviolet--to--Near-Infrared Spectral Flux Distribution of Four BL Lacertae Objects
Maraschi, L.; Tanzi, E. G.; Chiappetti, L.; Pian, E.; Falomo, R.; Treves, A.
Italy
Abstract
We report on simultaneous UV, optical, and near-IR observations of four BL Lac objects. For three objects (PKS 0118-27, PKS 0301-24, and PKS 1538+14), we find that the spectral flux distribution from 8 x 10^13^ to 2.5 x 10^15^ Hz is well described by a single power law with spectral index α_v_ = 1.2, α_v_ = 1.0, and α_v_ = 1.3, respectively. For H0323 +02, after subtraction of the contribution due to the host galaxy, the spectral emission is again consistent with a single, flatter power law, α_v_ = 0.78.