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Speckle interferometry of HIPPARCOS link stars - III.
White, G. L.; Argue, A. N.; Reynolds, J. E. +5 more
A third list of stars is presented which have been tested by speckle interferometry for use in the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the extragalactic VLBI reference frame. Structural information on angular scales of 0.15-1.2 arcsec for 34 Southern Hemisphere stars is reported from observations made …
The missing UV absorption lines of NGC 4151.
Penston, M. V.; Snijders, M. A. J.; Leech, K. J.
In this paper we discuss new, near-simultaneous high-dispersion long- and short- wavelength International Ultraviolet Explorer (IUE) observations of the Seyfert galaxy NGC 4151. Previous observations revealed a narrow absorption system in Mg II not present in Lyα or C IV. The new observations confirm the presence of this system in Mg II and its ab…
Erratic profiles of type II bursts of very low fluence from the rapid burster.
Lewin, Walter H. G.; van Paradijs, Jan; Lubin, Lori M. +2 more
Results are presented of approximately 17 hr of Exosat observations of the Rapid Burster in September 1985 during which about 541 type II bursts lasting less than 30 s were observed. Although these bursts are known to have an approximately time-invariant profile showing successive peaks in the burst's decay portion, most of the 20-s bursts at the …