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X-Ray Variability of the Bright Bl-Lacertae Object PKS2155-304
Maccagni, D.; Maraschi, L.; Tanzi, E. G. +3 more
We have observed the BL Lac object PKS 2155-304 with the EXOSAT observatory and with IUE on 1983 October 31 and November 29. At the same time, optical photometry has been obtained. Variability has been observed both on a time scale of hours during the October 31 observation and on the time scale of one month. During the November 29 observation the…
EXOSAT Observations of the Contact Binary Vw-Cephei
Heise, John; Vilhu, Osmi
EXOSAT observations of the contact binary VW Cephei on 19th March 1984 are presented. The L1-telescope with CMA+thick Lexan filter was used. The observations cover one orbital revolution showing an asymmetrical X-ray light curve. This can be modelled by an active neck, connecting the two stars, and with enhanced coronal regions on the primary star…
X-Ray Optical and Ultraviolet Observations of the Am-Herculis System E2003+225
Mukai, K.; Maraschi, L.; Chiappetti, L. +13 more
The AM Her type object E2003+225 was observed with EXOSAT, IUE and ground-based telescopes on 1983 Oct. 12. The brightness of the ultrasoft X-ray component allowed the Objective Grating Spectrometer (OGS) to be used, which gave a model-independent determination of the temperature of the blackbody spectrum. The star was observed again on 1984 July …
Simultaneous EXOSAT-IUE observations of NGC 4151
Tarenghi, M.; Piro, L.; Perola, G. C. +9 more
NGC 4151 was observed four times in Nov. 83. The results indicate that: a) there exists a correlation between the X-ray and UV fluxes on the long term; b) the soft X-ray excess between 0.1 and 1 keV is probably steeper than expected from the leaky absorber model by Holt et al (1980); c)the spectral fit to the ME data, after correction for a soft c…