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Ultraviolet and X-ray observations of the BL Lac object MK 501.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +3 more
We present ultraviolet and X-ray satellite observations of Mk 501. The ultraviolet data after dereddening assuming E(B-V) = 0.11 show a power-law spectrum with α = 0.51+0.10-0.15. The visible and infrared fluxes are in good agreement with this power-law if the underlying elliptical galaxy has a luminosity MV = -22.…
Far ultraviolet line profiles in the Seyfert galaxy NGC 4151.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +2 more
Two high-resolution far-UV spectra (1150-2000 A) of the Seyfert 1 galaxy NGC 4151 are presented which were obtained from the IUE satellite with a resolution of about 10,000. It is found that the Ly-alpha line in NGC 4151 is asymmetric and rather narrow, that the Ly-alpha/H-beta ratio varies across the line, and that there are two absorption system…
The [Ne IV] 2D -> 4S lines in the planetary nebula NGC 7662.
Lutz, J. H.; Seaton, M. J.
Results are reported for high-resolution IUE satellite observations of the 2p 3 2D 3/2 - 4S, 2D 5/2 - 4S UV forbidden lines of Ne IV in the spectrum of NGC 7662. Precision measurements of the wavelengths are obtained, along with an improved determination of Ne IV doublet-quartet separations, a measurement of the intensity ratio for the forbidden N…
Gamma rays from the Cygnus region and the nature of CG 78+1.
Strong, A. W.; Wolfendale, A. W.; Protheroe, R. J.
Interpretation of the galactic gamma-ray flux above 100 MeV has been complicated by the presence of a component due to 'point' sources of gamma-rays and by the lack of measurements of the molecular hydrogen (except along the galactic equator) which forms a large fraction of the interstellar medium (ISM). Recent CO observations of the Cygnus X regi…
A geometrical analysis of the gamma-ray light curves of pulsars.
Massaro, E.; Buccheri, R.; Salvati, M.
In the light curves of the COS-B gamma-ray pulsars, some common features are clearly recognizable; two main peaks always occur, and the intervening phase lag has not the natural value of 0.5. An interpretation is proposed which only involves a simplified geometrical description of the emission pattern, viz. two opposite hollow cones with a first-o…