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BL Lac Objects and Blazars: Past, Present, and Future
C. Megan Urry
The past 20 years have seen phenomenal progress in our understanding of BL Lac objects. They form part of the blazar class, which are radio-loud AGN whose relativistic jets are ali…
HST snapshot imaging of BL Lac objects
R. Falomo, C. Megan Urry, Riccardo Scarpa +2
Snapshot images of about 100 BL Lac objects were obtained with WFPC2 on HST. Sources from various samples, in the redshift range 0.05 to 1.2, were observed and 61 resolved (51 with…
Fast X-ray Variability of PKS 2155-304: A Cross Correlation Analysis
A. Treves, Y. H. Zhang, A. Celotti +7
PKS 2155-304 is one of the prototypes of BL Lac objects. Its spectral energy distribution is known from the radio to the TeV band and has two peaks, one in the soft X-rays and the…
BeppoSAX Observations of the BL Lac Object Mkn 501 in an Intermediate State
Elena Pian, Eliana Palazzi, Lucio Chiappetti +8
The BL Lac object Mkn 501 was observed with the BeppoSAX satellite at three epochs in April-May 1998, simultaneously with the Whipple and HEGRA Cherenkov telescopes. The X-ray spec…
ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)
Rita M. Sambruna, G. Ghisellini, Eric Hooper +3
We present ASCA observations of the radio-selected BL Lacertae objects 1749+096 (z=0.32) and 2200+420 (BL Lac, z=0.069) performed in 1995 Sept and Nov, respectively. The ASCA spect…
Ultraviolet Isotropic Emission from the Blazar 3C 279
E. Pian, A. Koratkar, L. Maraschi +7
Archival IUE SWP and HST FOS spectra show the presence of a relatively strong, broad Lyman alpha emission line superposed onto the UV spectral continuum of the blazar 3C 279. As op…
BeppoSax Spectral Survey of soft X-ray selected BL Lacs
A. Wolter, A. Comastri, G. Ghisellini +10
We present X-ray spectra obtained with BeppoSAX (Satellite per Astronomia X) of 10 BL Lac objects, selected from the Einstein Medium Sensitivity and Slew Surveys. We find that in a…
BeppoSAX Observations of the TeV Blazar Mkn 421
G. Fossati, L. Chiappetti
The blazar Mkn 421 has been observed, as part of the AO1 Core Program, five times from 2 to 7 May 1997. In the LECS+MECS energy band the spectrum shows convex curvature, well repre…