GCN Circular 7090
Stefano Sposetti (Gnosca, Switzerland) reports to the AAVSO International High Energy Network the following optical observations of GRB071112C (GCN #7059, Perri et al.): Stefano Sposetti reports the detection of the optical afterglow of GRB071112C (Perri et al., GCN 7059, and several subsequent reports). The afterglow was observed unfiltered for 2700 seconds, using a 0.4-meter Newtonian with an SBIG ST8XE CCD and no filter. Observations commenced approximately 4 hours and 10 minutes post BAT detection; the midpoint of the observational sequence was 2007 November 12.9625 UT. The afterglow was detected at an unfiltered magnitude of 21.0 +/- 0.5, calibrated relative to USNO-A2.0. This magnitude is consistent with the reported detection by Greco et al. (GCN #7089) on November 12.929 UT at Rc = 21 +/- 0.2. A detailed report on these observations is available on the AAVSO website at ftp://ftp.aavso.org/grb/StefanoSposetti_GRB071112C_2454419.20588_.txt A fits image is available at ftp://ftp.aavso.org/grb/StefanoSposetti_GRB071112C_2454419.20588_.fits The AAVSO thanks the Curry Foundation for their continued support of the AAVSO International High Energy Network.