2007A&A...464L..25C

A good fraction of GRBs detected by Swift have a high redshift (up to z=6.3, so far). Their study allows us to investigate, among other things, cosmic star formation in the early Universe (possibly up to the re-ionization era) and the chemical enrichment of the high-redshift gas. Here we present and discuss a selection procedure that identifies high-redshift (z>5) candidates based only upon the promptly-available information provided by Swift. This method relies upon Galactic extinction, GRB duration, and the absence of an optical counterpart in the UVOT telescope onboard Swift. This tool may provide an extremely effective way to locate high-redshift astrophysical objects and to follow them in the optical/NIR band in near real time.