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Multifrequency observations of the BL Lacertae object PKS 0537-441.
Maraschi, L.; Tanzi, E. G.; Treves, A. +1 more
PKS 0537 - 441 was repeatedly observed in the UV band with the International Ultraviolet Explorer and in the X-ray with the Einstein Observatory. On September 27, 1980, simultaneous observations in the two bands were obtained. Near-infrared photometry preceding and following the simultaneous observations by about one month is available from the li…
Temporal variations in UV spectra of the red giant C star, TW Hor.
Querci, M.; Querci, F.
The time behavior of ultraviolet emission lines in the cool carbon star TW Hor is discussed. The emission lines were obtained over a three year period using the International Ultraviolet Explorer (IUE) spacecraft in the wavelength range 2100-3300 A. All the lines are found to vary in time (on scales of about one hour to two months) without any app…
Spectroscopy and spectrophotometry of the nova-like system V3885 Sagittarii.
Drechsel, H.; Haug, K.
New optical and UV observations of the novalike variable V3885Sgr are analyzed. The line identifications and radial velocity measurements are presented, and the Balmer, He I, and He II line profiles are investigated. Physical parameters of the system are derived, and spectrophotometric light curves are presented. The continuum flux distribution be…
EXOSAT Medium-Energy Observations of CYGNUS-X-2
Pietsch, W.; Hasinger, G.; Sztajno, M. +1 more
On July 5. 6. 1983, during the EXOSAT performance verification (PV) and calibration phase, a raster scan of Cygnus X-2 was performed. In contrast to the previously observed smooth intensity variations on timescales of hours, the source revealed a behaviour unknown until now: active periods with high energy flares recurring on time scales of 300 50…
X-ray emission from the planetary nebula NGC 1360
Jansen, F. A.; McKechnie, S. P.; de Korte, P. A. J. +1 more
The EXOSAT observatory has detected the nucleus of NGC 1360 in four photometric energy bands. The data rules out that the emission is from blackbody origin. Initial fits made with LTE model atmosphere spectra require the presence of highly ionized Oxygen and Neon in the stellar atmosphere.
The in-orbit performance of the Exosat gas scintillation proportional counter
Manzo, G.; Taylor, B. G.; Peacock, A. +2 more
The European X-ray observatory satellite Exosat, launched in May 1983, carries a scientific payload of four instruments designed to study the properties of cosmic X-ray sources. The present investigation is concerned with one of these instruments, taking into account the gas scintillation proportional counter (GSPC) spectrometer. Attention is give…
The Lyman alpha emission in W Ursae Majoris.
Whelan, J. A. J.; Vilhu, O.; Rucinski, S. M.
The paper presents results of reductions of six low resolution IUE-SWP spectra properly exposed at Ly-alpha during one orbital revolution of WUMa, the prototype for late-type contact binaries. Two different methods have been used to eliminate the geocoronal contribution to the emission line. The effect of the interstellar H I absorption has been m…
The ultraviolet variability of the BL Lacertae object OJ 287.
Coe, M. J.; Hanson, C. G.
The International Ultraviolet Explorer (IUE) satellite has been used to observe the BL Lacertae object, OJ287, at 26 epochs between 1978 May and 1984 May. These observations how large and often rapid variations in both the intensity and the spectral slope of the UV continuum. In general, the changes in intensity show little or no correlation with …
Ultraviolet studies of stars in the populous cluster NGC 2100 in the Large Magellanic Cloud.
Bohm-Vitense, E.; Proffitt, C.; Hodge, P.
The authors have studied the ultraviolet energy distributions of the B stars in the LMC cluster NGC 2100. The ultraviolet extinction law was studied for the LMC cluster. The Teff-luminosity diagrams were determined. The brightest stars in the clusters are evolved stars on the "horizontal" supergiant branch. No P Cygni profiles indicatin…
Hard X-Ray Observations of the Eclipsing Binary Ex-Hydrae
Beuermann, K.; Osborne, J.
The authors present light curves of EX Hydrae in the 1 - 10 keV range obtained with the medium energy experiment of EXOSAT. The 67-min modulation was observed with a peak-to-peak amplitude of 36% in the 1 - 4 keV range and of 24% in the 4 - 9 keV range. Newly discovered was a partial X-ray eclipse of ≡3 min full width which coincides with the opti…