TITLE: GCN CIRCULAR NUMBER: 7423 SUBJECT: GRB080310, LBT and MDM photometry DATE: 08/03/17 01:52:38 GMT FROM: Peter Garnavich at U of Notre Dame G. Wegner (Dartmouth), P. Garnavich (Notre Dame), J. L. Prieto, and K. Z. Stanek (OSU) report: We observed the position of GRB 080310 (Chornock et al. GCN 7381; Cummings et al., GCN 7382) with the Large Binocular Telescope (LBC red and blue cameras) on March 13.40 (UT) and with the MDM 2.4-m Hiltner telescope (Retrocam) on March 14.39 (UT) through Sloan-r filters. Using stars calibrated by the SDSS, we estimate the following r-band magnitudes: age (days) r mag error telescope 3.04 22.45 0.05 LBT 4.03 23.10 0.10 MDM The photometry indicates that the afterglow has resumed a steep decline. Including LBT photometry from March 12 (Garnavich et al., GCN 7414), we estimate a power-law decline index of 2.1 between 2 and 4 days after the burst. A plot of the light curve is available at: http://www.nd.edu/~pgarnavi/LBT/grb080310/LBT_lightcurve.jpg The LBT is an international collaboration among institutions in the United States, Italy and Germany. The LBT Corporation partners are: * The University of Arizona on behalf of the Arizona university system * Istituto Nazionale di Astrofisica, Italy * LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University * The Ohio State University * The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia This message may be cited.