We report the results of optical monitoring of a sample of AGNs carried out in summer 2002. While rapid optical variability is a well-known aspect of blazar activity, there have been fewer studies of possible rapid variations in the spectrum, although some studies suggest that variations may exist even on scales of hours and less. Six of fourteen

We present a revised and augmented version of the Gonzalez-Perez et al. [AJ 122 (2001) 2055] catalogue of stars in quasar and blazar fields calibrated in the Landolt system. Several of the sources in this catalogue are known TeV emitters and thus of considerable interest for multifrequency campaigns. A total of 8000 measures in BVRI have been added

SAX J1747.0-2853 is an X-ray transient which exhibited X-ray outbursts yearly between 1998 and 2001, and most probably also in 1976. The outburst of 2000 was the longest and brightest. We have analyzed X-ray data sets that focus on the 2000 outburst and were obtained with BeppoSAX, XMM-Newton and RXTE. The data cover unabsorbed 2-10 keV fluxes

The neutron star binary SAX J1747.0-2853, located in the Galactic Center region at about 0.5 deg from Sgr A* and at a distance of ˜9 kpc, has been observed in outburst four times (1998, 1999, 2000 and 2001) by BeppoSAX and RossiXTE. At the time of its discovery in 1998 the source was observed in a low/hard state, showing a hard tail with a high

We present the results of a search for variable stars in the Local Group dwarf galaxy Phoenix. Nineteen Cepheids, six candidate long-period variables, one candidate eclipsing binary, and a large number of candidate RR Lyrae stars have been identified. Periods and light curves have been obtained for all the Cepheid variables. Their distribution in

We discuss the different physical processes contributing to the infrared continuum of active galactic nuclei (AGNs), assuming that both photoionization from the active centre and shocks ionize and heat the gas and dust contained in an ensemble of clouds surrounding the nucleus. In our model, radiation transfer of primary and secondary radiation