CCD photometry of 18 Jupiter family comets, observed at medium and large heliocentric distances, was carried out between April 1990 and July 1995. This is part of a long-term observational program designed to obtain their nuclear magnitudes. The observations were made with the 1.54-m Danish Telescope at ESO La Silla, the 2.5-m Nordic Optical

We present 53 simultaneous photometric (I band) and spectroscopic (6900-9500Å) observations of GRO J0422+32, taken during 1997 December. From these we determine that J0422+32 was in its lowest state yet observed, at I=20.44+/-0.08. Using relative spectrophotometry, we show that it is possible to correct very accurately for telluric absorption

We analyze the Zff vertex in the framework of models that add a new bottom quark in a non-sequential way and we evaluate the tree level contribution to the LEP/SLC observables ΓZ, Rb and Rl. We obtain bounds for the mixing angles from the experimentally allowed contour regions of the parameters ΛL,R introduced here. In order to get a more

The calibration of ISOPHOT observations is hampered in many cases by the transient response of the detectors. Here we outline the behaviour observed in flight for the different ISOPHOT detectors. We also present some of the procedures which are currently used to correct transient effects and their implementation in the ISOPHOT Interactive Analysis.

We report spectral time series of the late O-type runaway supergiant HD 188209. Radial velocity variations of photospheric absorption lines with a possible quasi-period of ~6.4d have been detected in high-resolution echelle spectra. Night-to-night variations in the position and strength of the central emission reversal of the Hα profile occurring

Low-frequency radio surveys are ideal for selecting orientation-independent samples of extragalactic sources because the sample members are selected by virtue of their isotropic steep-spectrum extended emission. We use the new 7C Redshift Survey along with the brighter 3CRR and 6C samples to investigate the fraction of objects with observed broad