RXTE highlights of 34.85-day cycle of Her X-1

An analysis of the publically available RXTE archive on Her X-1 including data on 23 34.85-day cycles is performed. The turn-on times for these cycles are determined. The number of cycles with a duration of 20.5 orbits has been found exceedingly larger than of shorter (20 orbits) or longer (21 orbits). A correlation between the duration of a cycle and its mean X-ray flux is noted. The mean X-ray light curve shows a very distinct short-on state. The anomalous X-ray absorption dip is found during the first orbit after the turn-on in the main-on state for the cycles starting near the binary phase 0.25, while is present during two successive orbits in the low-on state. The post-eclipse recovery feature have not been found in the main-on state but appears at least for two orbits during the low-on state. The pre-eclipse dips are present both in main-on and low-on state and demonstrate the behaviour as in early observations. The comparison of durations of the main-on and short-on states enabled us to constrain the accretion disk semi-thickness and its inclination to the orbital plane.Comment: 7 pages with 4 eps figures (large figures 1, 4a,b, 5a,b are available at ftp://xray.sai.msu.su/pub/preprints/Prokhorov/rxte/ or at ftp://xray.sai.msu.ru/pub/preprints/Prokhorov/rxte/), LaTeX, uses mn.sty. Submitted to MNRA

Gravitational wave background from coalescing compact stars in eccentric orbits

Stochastic gravitational wave background produced by a stationary coalescing population of binary neutron stars in the Galaxy is calculated. This background is found to constitute a confusion limit within the LISA frequency band up to a limiting frequency \NUlim{}\sim 10^{-3} Hz, leaving the frequency window $\sim 10^{-3}$--$10^{-2}$ Hz open for the potential detection of cosmological stochastic gravitational waves and of signals involving massive black holes out to cosmological distances.Comment: 6 pages, 7 figure