Search Publications
The European X-ray Astronomy Satellite EXOSAT: programme status.
Peacock, A.
The current status of the European X-ray Astronomy Satellite programme, EXOSAT, which includes the payload, spacecraft and ground segment are summarised. Details of the experiment performances and sensitivities are provided.
The radial distribution of gamma rays and cosmic rays in the outer Galaxy
Hermsen, W.; Bloemen, J. B. G. M.; Blitz, L.
The radial distribution of the high-energy (70 MeV-5 GeV) gamma-ray emissivity in the outer Milky Way is derived. The kinematics of HI are used to construct column-density maps in three galacto-centric distance ranges in the outer Galaxy. These maps are used in combination with COS-B gamma-ray data to determine gamma-ray emissivities in these dist…
Radial velocity of HD 77581 (Vela X-1) in the period of 1972 - 1983.
Matsuoka, M.; Sadakane, K.; Jugaku, J.
The radial velocity of HD 77581 (Vela X-1 = 4U 0900-40) was derived from photospheric Fe Iv and Fe II lines observed by the International Ultraviolet Explorer (IUE) satellite in the period 1978-1983. No long-term variation in the radial velocity of 30 km/s was observed. It is shown that the absence of variation effectively rules out the possibilit…
The galactic distribution of cosmic-ray particles
Hermsen, W.; Bloemen, J. B. G. M.
COS-B gamma-ray observations are compared with large-scale HI and CO surveys in different regions of the sky to derive information on the cosmic-ray density distribution throughout the Galaxy and/or a calibration of the ratio between H2 column density and integrated CO line intensity [N(H2)/Wco]. In the region of t…
Broad-band X-ray spectrum of the bright Seyfert galaxy MKN 509
Molteni, D.; Robba, N. R.; Sacco, B. +1 more
One of the brightest X-ray Seyfert galaxies, Mkn 509, has been observed with the X-ray satellite EXOSAT. Wide-band (0.05 - 35 keV) spectral information is now available at the same time. Different filters have been rotated in front of the low-energy telescope. The overall spectrum is best fitted by a two-component power law. The intensity and the …
The EXOSAT and Einstein observations of 1E0630 + 178 ('Geminga') as complementary data sets
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +1 more
Data for the soft X-ray source 1E0630 + 178 are now available from four independent measurements of the Einstein and EXOSAT missions. These are presented and compared in the light of the different characteristics and energy response of the different X-ray imaging detectors used (IPC, LE 1, LE 2). The time variability on medium (hours) time scale i…
CA II K emission in Canopus.
Bappu, M. K. V.; Mekkaden, M. V.; Rao, N. K.
The changes in the Ca II K line profile of the F0 supergiant Canopus have been studied from the high dispersion coude spectrograms obtained since 1975. The emission in the core of the line is variable in a timescale of few days. Similar activity seems to be occurring in Mg II h and k lines also. This is attributed to the variability in the appeara…
Three gamma-ray sources with large angular sizes
Li, T. -P.
From an analysis of the data from the gamma-ray satellite COS-B and from radio measurements of CO molecules, it appears probable that the three gamma-ray sources 2CG 036+01, 218-00, 235-01 are either isolated giant molecular clouds or superpositions of clouds unresolved by the detector.
An ultraviolet identification list for the AP star IOTA Cassiopeiae.
Jasinski, M.; Woszczyk, A.
The authors present a detailed identification of the absorption lines in the ultraviolet spectrum of ι Cas. The list contains 412 lines. The identified lines belong mainly to iron and chromium. Also many lines of manganese are present.
Background-sensitive event selection in the search for gamma-ray sources
Özel, M. E.; Mayer-Haßelwander, H. A.
Poor angular resolution of present day gamma ray telescopes (1° at 100 MEV) together with the complicated gamma ray sky structures at compareable angular extents and poor statistics available necessitate the selection of those gammas which will increase the observable signal from a suspected source. A method for such a selection using the pre-know…