Optical Transients from gamma-ray burst sources, in addition to offering a distance determination, convey important information about the physics of the emission mechanism, and perhaps also about the underlying energy source. As the gamma-ray phenomenon is extremely diverse, with timescales spanning several orders of magnitude, some diversity in

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RXJ 2117+3412 is a transition object between the planetary nebulae and the white dwarfs. The central star is a pulsating PG 1159 type star. We summarize here the results of the campaigns organized between 1992 and 1994. We identify about 50 modes, most of them probably belonging to l = 1. The derived mass of the star is 0.57 Msun. Its distance can

Central line wavelengths in the spectrum of the Sun observed at the centre of the disc, and in the flux spectrum, line identification and solar log(gf). (1 data file).

In non-equilibrium plasma spectroscopy it may happen to have to deal with ensembles of particles, whose velocity distribution is not the equilibrium (i.e. Maxwell) one. Consequently, the shape-profile-of the relevant emission or absorption coefficient is different from the profile (Gauss or Voigt) that corresponds to the equilibrium velocity