NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344

SAX and multiwavelength observations of BL Lacertae in 2000

We present two BeppoSAX observations of BL Lac (2200+420) as part of a multiwavelength campaign performed in 2000. The source was in different states of activity: in June, the X–ray spectrum was faint and hard (α ∼ 0.8), with positive residuals towards low energies. In October we detected the highest [2–10] keV flux ever measured for the source. During this observation, the spectrum was soft (α...

Multiwavelength Observations of the BL Lacertae Object PKS 2155 – 304 with XMM - Newton

The optical-UV and X-ray instruments on-board XMM-Newton provide an excellent opportunity to perform simultaneous observations of violently variable objects over a broad wavelength range. The UV and X-ray bright BL Lac object PKS 2155–304 has been repeatedly observed with XMM-Newton about twice per year. In this paper, we present a detailed analysis of the simultaneous multi-wavelength variabil...

Modeling the Variability of the Bl Lacertae Object Pks 21552304

The bright X-ray–selected BL Lacertae object PKS 21552304 has been the target of two intense multiwavelength campaigns: in 1991 November and in 1994 May. Although the spectral energy distributions at both epochs were quite similar, the source exhibited two very distinct variability patterns that cannot be easily reconciled with homogeneous, one-zone jet models. During the first epoch the variab...

Spectral variability and multiwavelength studies of the high-frequency-peaked BL Lacertae object 1ES 0806+524 with the MAGIC telescopes

Modeling the Multiwavelength Spectra and Variability of BL Lacertae in 2000

BL Lacertae was the target of an extensive multiwavelength monitoring campaign in the second half of 2000. The campaign had revealed optical and X-ray intraday variability on time scales of ∼ 1.5 hours and evidence for significant spectral variability both at optical and X-ray frequencies. During the campaign, BL Lacertae was observed in two different activity states: A quiescent state with rel...