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Simultaneous UV, optical and radio monitoring of the BL Lac object OJ 287 in March 1993
Maraschi, L.; Pian, E.; Quirrenbach, A. +26 more
The BL Lacertae object OJ 287 was intensively monitored with the IUE satellite from 1993 March 15 to 20 in the 2000-3000 Angstroms wavelength region. The very low emission state of the source hampered the detection during part of the 23 performed exposures. The light curve at 2650 Angstroms constructed with the 11 best images exhibits a variable t…
The broad band energy distribution of the misaligned gamma-ray blazar PKS 0521-365
Maraschi, L.; Ghisellini, G.; Pian, E. +4 more
Simultaneous UV and X-ray observations of the blazar PKS 0521-365 are combined with radio, IR, optical and gamma-ray data taken at different epochs to study the overall emission from 10^9 to 10^23 Hz. The energy distribution declines from the IR to the UV range (alpha_opt-UV = 1.4 +/- 0.1), buthardens at higher frequencies. The remarkably flat X-r…
Ultraviolet eclipse observations of an accretion disk wind
Raymond, J. C.; Mason, K. O.; Cordova, F. A. +3 more
We present eclipse time series of ultraviolet Civ 1549Angstroms and Heii line profiles in the spectrum of the nova-like variable UX UMa, obtained using the Goddard High Resolution Spectrometer (GHRS) on board the Hubble Space Telescope (HST). These data provide important new insights into the origin of these mainly wind-formed lines. Specifically,…