Water maser variability over 20 years in a large sample of star-forming regions: the complete database^*

¹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: cesa@arcetri.astro.it
² INAF – Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
³ INAF – Istituto di Radioastronomia, Sez. di Firenze, Largo E. Fermi 5, 50125 Firenze, Italy
⁴ Dipartimento di Astronomia, Università degli Studi di Firenze, Largo E. Fermi 2, 50125 Firenze, Italy

Received: 7 May 2007
Accepted: 3 July 2007

Abstract

Context.Water vapor emission at 22 GHz from masers associated with star-forming regions is highly variable.

Aims.We present a database of up to 20 years of monitoring of a sample of 43 masers within star-forming regions. The sample covers a large range of luminosities of the associated IRAS source and is representative of the entire population of H₂O masers of this type. The database forms a good starting point for any further study of H₂O maser variability.

Methods.The observations were obtained with the Medicina 32-m radiotelescope, at a rate of 4-5 observations per year.

Results.To provide a database that can be easily accessed through the web, we give for each source: plots of the calibrated spectra, the velocity-time-flux density plot, the light curve of the integrated flux, the lower and upper envelopes of the maser emission, the mean spectrum, and the rate of the maser occurrence as a function of velocity. Figures for just one source are given in the text for representative purposes. Figures for all the sources are given in electronic form the appendix. A discussion of the main properties of the H₂O variability in our sample will be presented in a forthcoming paper.