<title>In memory of Bohdan Paczynski</title>

Abstract

Sessions XIV and XV of the XX^th Wilga Symposium were devoted to the Pi of the Sky project, aimed at massive automated photometry of celestial objects. The original goal of the project was early detection of optical afterglows from gamma-ray bursts, but it soon expanded into a general survey of all kinds of fast astronomical phenomena occurring above a certain limiting magnitude. The idea stems from two ingenious suggestions by late Professor Bohdan Paczynski: that gamma bursts are extragalactic phenomena (therefore, they are extremely energetic and equally extremely interesting), and that the classical observational approach (big telescopes, long exposures, small areas of the sky) should be supplemented by "massive photometry", with many small telescopes quickly repeating observations of large areas of the sky (in a desirable limit - of the whole sky). Paczynski was not personally involved in Pi of the Sky, but as the spiritual father of the project, and as one of the greatest contemporary astrophysicists, he certainly deserves to be remembered here.