We imaged the X-ray error box of GRB 980703, beginning 22.5 hr after the gamma-ray event, in both the optical R and near-infrared H bands. A fading optical/IR object was detected within the X-ray error box, coincident with the variable radio source reported by Frail et al. in 1998, who also detected the optical transient independently of us

We present a study of the trends in luminosity, linear size, spectral index, and redshift of classical double radio sources, from three complete samples selected at successively fainter low radio-frequency flux limits. We have been able to decouple the effects of the tight correlation between redshift and luminosity (inherent in any single flux

Four planetary nebulae (PNe) with conspicuous point-symmetric morphology are studied in this paper through high-quality imagery and long-slit echelle spectroscopy. Point symmetry is also found in the velocity space, and this is related to particular forms of bipolar collimated outflows. Morphology and kinematics together reveal the presence of

We have acquired [O III] lambda5007, H I lambdalambda6563 and 4861, and [S II] lambdalambda6717 and 6731 imaging of the bipolar outflow source NGC 6445. As a result, we find that density is preferentially enhanced within an interior optical/radio emission annulus and takes a maximum value ~1.1x10^3 cm^-3. Visual extinction appears also to be

We consider here a representative set of delta Scuti stars observed in the Praesepe cluster, thanks to recent efforts of multi-site networks. We show that the effect of rotation on the determination of fundamental parameters {Mbol} and {Teff} cannot be neglected when modelling fast rotators as delta Scuti stars. We propose a method to take this

We report the first reliable measurement of the nebular [O i] lambda 5577 emission line in the Orion nebula. Diagnostic diagrams based on the [O i] lambda lambda 5577, 6300, and [N i] lambda lambda 3467, 5198, 5200 emission lines indicate that the bulk of the nebular emission in the partially ionized zone of the Orion nebula is produced in regions