12 papers
Demographics of Blazars
G. Fossati
We discuss the preliminary results of an extensive effort to address the fundamental, and yet un-answered, question that can be trivialized as: ``are there more blue or red blazars…
Looking for High Energy Peaked Blazars
L. Costamante, G. Ghisellini, A. Celotti +10
Blazars can be classified on the basis of their overall Spectral Energy Distribution (SED). BL Lac objects are usually divided in LBL or HBL (Low or High energy peaked BL Lacs), ac…
The concave X-ray spectrum of the blazar ON 231: the signature of intermediate BL Lac objects
G. Tagliaferri, G. Ghisellini, P. Giommi +17
ON 231 was observed with BeppoSAX in May and June 1998, following an exceptional optical outburst which occured in April--May. We measured the X-ray spectrum from 0.1 up to 100 keV…
X-ray Rapid Variability of MKN 421
A. Treves, Y. H. Zhang, F. Tavecchio +7
We present a detailed Cross Correlation analysis of the light curves of the X-ray bright BL Lac object Mkn 421 observed with SAX period 1997-1998. Monte Carlo simulations ar…
Hour-Scale Multiwavelength Variability in Markarian 421
M. Catanese, I. H. Bond, S. M. Bradbury +36
Markarian 421 was observed for about four days with BeppoSAX and the Whipple Observatory gamma-ray telescope in April 1998. A pronounced, well-defined, flare with hour-scale variab…
The blazar PKS 0528+134: new results from BeppoSAX observations
G. Ghisellini, L. Costamante, G. Tagliaferri +14
BeppoSAX observed 8 times the gamma-ray bright blazar PKS 0528+134 in Feb. and Mar. 1997, during a multiwavelength campaign involving EGRET, onboard CGRO, and ground based telescop…