We have conducted deep photometric searches for substellar members of the Praesepe (0.5-1 Gyr) and σ Orionis (3 Myr) star clusters using the Sloan i' and z' broad-band filters, with the 3.5-m and the 5-m Hale telescopes on the Calar Alto and Palomar Observatories. The total area surveyed was 1177 arcmin2 and 1122 arcmin2 towards the central regions

We present observations and an interpretative model of the dust environment of the Main-Belt Comet P/2010 F5 (Gibbs). The narrow dust trails observed can be interpreted unequivocally as an impulsive event that took place around 2011 July 1 with an uncertainty of ±10 days, and a duration of less than a day, possibly of the order of a few hours. The

A brief description is given of the IMAGE-1 software package for the presentation and evaluation of digitized images at the Osservatorio Astronomico di Trieste. The package makes it possible to draw isophotes in an interactive way and to have an assonometric display of the image studied.

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We present a detailed photometric study of the dwarf irregular galaxy NGC 6822 aimed at investigating the properties of its stellar populations and, in particular, the presence of stellar radial gradients. Our goal is to analyse the stellar populations in six fields, which cover the whole bar of this dwarf galaxy. We derived the quantitative star

On a recent spectrogram of the planetary nebula NGC 6572 the authors have found He II 4686 clearly in emission. They review previous descriptions of the spectrum and conclude that He II 4686 is stronger than 20 years ago. They briefly discuss the possible implications of this result, and suggest a careful monitoring of several planetary nebulae.