Observations with the Swift UVOT have unambiguously uncovered for the first time a long-lived, UV "plateau" in a Type II-P supernova (SN). Although this flattening in slope is hinted at in a few other SNe, due to its proximity and minimal line-of-sight extinction, SN 2012aw has afforded the first opportunity to clearly observe this UV plateau. The observations of SN 2012aw revealed all Swift UV and u-band lightcurves initially declined rapidly, but 27 days after explosion the light curves flattened. Some possible sources of the UV plateau are: the same thermal process that cause the optical plateau, heating from radioactive decay, or a combination of both processes.
@article{arxiv.1210.5496,
title = {The Long-Lived UV "Plateau" of SN 2012aw},
author = {Amanda J. Bayless and Tyler Pritchard and Peter W. A. Roming and Paul Kuin and Peter J. Brown and Maria Teresa Botticella and Massimo Dall'Ora and Lucille H. Frey and Wesley Even and Chris L. Fryer and Justyn R. Maund and Morgan Fraser},
journal= {arXiv preprint arXiv:1210.5496},
year = {2015}
}