The authors present simultaneous UBVRI and infrared JHKL light curves of the short-period RS CVn system ER Vul, and study both the mean level and depths of eclipses. They also point out some peculiar features, present in the light curves over time, which are frequently shown by other RS CVn short-period systems at about the same phase values

An improved error box of GRB 970815 has been reported very recently (Smith et al.1999). This error box is consistent with the decaying X-ray source detected by ROSAT, which strongly supports the source as the GRB X-ray afterglow. We report a re-analysis of the follow up observations performed in 1997 containing the improved RXTE error box. No

We report differential I-band and J-band photometry of S Ori 45, a cool (spectral type M8.5), young (1-8 Myr) brown dwarf of the sigma Orionis cluster with a likely mass estimated at around 20 times the mass of Jupiter. We detect variability (amplitudes ranging from 34 to 81 mmag) and observe a modulation at a period of 2.5-3.6 h in both optical

We present the photometric history of some Luminous Blue Variable candidate stars in M 33. The search for outbursts was made in photographic plates taken in the B band of the galaxy M 33 and cover an eight year period, 1982-1990. Twenty five plates, separated into seven groups, have been used. CCD UBV magnitudes of the star UIT003 are presented

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We have carried out multi-epoch, time-series differential I-band photometry of a large sample of objects in the south-east region of the young (˜3 Myr), nearby (˜350 pc) σ Orionis open cluster. A field of ˜1000 arcmin2 was monitored during four nights over a period of two years. Using this dataset, we have studied the photometric variability of