We show that SBS1150+599A is most probably a planetary nebula located in the Galactic halo (becoming PN G135.9+55.9). Our photoionization models indicate that its oxygen abundance is lower than 1/100 solar.

Planetary nebulae (PNe) have been used to trace the chemical evolution of galaxies, not only in the Milky Way (Esteban & Peimbert 1995 and references therein) but also in nearby galaxies (Dopita et al. 1997; Richer et al. 1999; Jacoby & Ciardullo 1999). Extragalactic PNe have also been used as secondary distance indicators by means of the planetary

The existence of an extended component of diffuse ionized gas (DIG) is a well-known property of spiral galaxies. The integrated ensuremath {{H}alpha } luminosity of the DIG is very high (accounting for ~ 50% of the total ensuremath {{H}alpha } emission in a galaxy), which makes it important to understand the origin of this diffuse component.

We have compared direct estimates of the ionizing photon flux from the stars observed within the H II region NGC 346 in the Small Magellanic Cloud with its observed H alpha luminosity using a series of photoionization models of the region. The tests were based on the use of the photoionization code Cloudy (Ferland 2000), aided by H, He, N, O, Ne, S

Available from the Minor Planet Center.

We conducted two multi-site campaigns for two previously poorly-studied rapidly oscillating Ap (roAp) stars, HD122970 and HD99563. In January-June 1998, we observed HD122970 with 7 telescopes at 6 observatories and obtained 119 hr of data. We decided to organise a larger campaign for the same star in the year 2001 (5 telescopes at 4 observatories