Program: GS-2006B-Q-41

The detection by the SuperMACHO Project of moving light echoes from centuries-old supernovae in the LMC, announced in 2005, opens up exciting avenues of investigation linking resolved supernova remnants with hitherto unobtainable photometric and spectrocopic data from the outburst itself. In this proposal, we build on the earlier success of Rest et al, Nature, 438, 1132 (2005) and the observations obtained with GMOS-S in semester 2005B in the following ways: 1) We will obtain MOS spectroscopy of SN1987A light echoes corresponding to a number of different dust sheet "heights" out to 1 kpc in front of the event to determine dust properties and a geometric distance to the LMC. 2) We will obtain spectra for a fourth ancient light echo system in the LMC, believed to be associated with a 1000 year-old SN remnant which had not yet been discovered when 2005B observations were proposed and obtained, and 3) We will obtain MOS spectroscopy of a highly-evolved late-type variable in the LMC, apparently similar to V838 Mon, which reveals moving light echoes in its immediate vicinity. This star was in one of the most densely observed MACHO Project fields and therefore a detailed lightcurve history between 1992 and 2000 exists. The Gemini spectroscopy will be complement proposed HST and SST observations. We emphasize that Gemini is uniquely suited to obtain the spectroscopy proposed herein and that the importance of this new observational technique in testing the limits of our understanding of all supernovae, but especially the Type Ia SN which provide the strongest evidence for an accelerating universe