Michael, EliMcCray, RichardPun, C. J.Garnavich, PeterChallis, PeterKirshner, Robert P.Raymond, JohnBorkowski, KazimierzChevalier, RogerFilippenko, Alexei V.Fransson, ClaesLundqvist, PeterPanagia, NinoPhillips, M. M.Sonneborn, GeorgeSuntzeff, Nicholas B.Wang, LifanWheeler, and Craig2019-09-252000Michael, Eli, Richard McCray, C. S. J. Pun, Peter Garnavich, Peter Challis, Robert P. Kirshner, John Raymond, et al. 2000. “[ITAL]Hubble Space Telescope[/ITAL] Spectroscopy of Spot 1 on the Circumstellar Ring of SN 1987A.” The Astrophysical Journal 542 (1): L53–56. https://doi.org/10.1086/312924.0004-637X1538-4357http://nrs.harvard.edu/urn-3:HUL.InstRepos:41399849We present ultraviolet and optical spectra of the first bright spot (P.A. = 29 degrees) on SN 1987A's equatorial circumstellar ring taken with the Space Telescope Imaging Spectrograph. We interpret this spot as the emission produced by radiative shocks that occur where the supernova blast wave strikes an inward protrusion of the ring. The observed line widths and intensity ratios indicate the presence of radiative shocks with velocities ranging from 100 to 250 km s(-1) entering dense (greater than or similar to 10(4) cm(-3)) gas. These observations, and future observations of the development of the spectra and line profiles, provide a unique opportunity to study the hydrodynamics of radiative shocks.en-USJournal Article2019-09-2510.1086/312924