Lecturer: Dr. Titus J. Galama Affiliation: University of Southern California Abstract: Gamma-ray bursts (GRBs) are short lived, extremely bright gamma-ray sources. Since their accidental discovery in 1973 with the Vela satellites they were an astrophysical enigma for nearly a quarter of a century. In 1997 softer and longer-lived afterglow emission was discovered at X-ray, optical, millimeter, and radio wavelengths. These observations enabled accurate localization of their counterparts and revealed that GRBs come from cosmological distances, that they are by far the most luminous photon sources in the universe, and that they are produced by the explosive deaths of very massive stars. I will present a personal story of what it was like to be at the forefront of a number of the very early discoveries made in this new field of afterglow studies, including the discovery of the very first optical afterglow (GRB 970228), the analyses of the first multi wavelength afterglow light curves and broad- band spectra, and the discovery of the connection of GRBs with very bright supernovae (hypernovae; GRB 980425 / SN 1998bw). Additional details of the upcoming Astrophysics' seminars can be found on the following link. ‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts. הצטרף: https://hangouts.google.com/hangouts/_/mail.huji.ac.il/astrophysics?hceid=bWFpbC5odWppLmFjLmlsX2c0czhydDlpcmhwZzRvdGNybWIzZGFqcjdvQGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20.dg5ikefvrl6v7p32unh969ngko&hs=121