A Search for Candidate Light Echoes: Photometry of Supernova Environments

Abstract

Supernova (SN) light echoes could be a powerful tool for determining distances to galaxies geometrically, Sparks 1994. In this paper we present CCD photometry of the environments of 64 historical supernovae, the first results of a program designed to search for light echoes from these SNe. We commonly find patches of optical emission at, or close to, the sites of the supernovae. The color distribution of these patches is broad, and generally consistent with stellar population colors, possibly with some reddening. However there are in addition patches with both unusually red and unusually blue colors. We expect light echoes to be blue, and while none of the objects are quite as blue in V-R as the known light echo of SN1991T, there are features that are unusually blue and we identify these as candidate light echoes for follow-on observations.