TITLE: GCN CIRCULAR NUMBER: 9999 SUBJECT: GRB 090812: Skynet/PROMPT and GORT Observations DATE: 09/10/08 04:54:57 GMT FROM: Josh Haislip at U.North Carolina J. Haislip, D. Reichart, K. Ivarsen, L. Cominsky, K. McLin, T. Graves, G. Spear, A. LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report: Skynet observed the Swift/BAT localization of GRB 090812 (Stamatikos et al., GCN 9768) with four of the 16" PROMPT telescopes at CTIO beginning 3.9 minutes after the trigger in UBVRI through variable cloud cover. Skynet continued observing with the 14" GORT telescope at Hume Observatory in California beginning 48.4 minutes after the the trigger in RI. We detect the afterglow (Stamatikos et al., GCN 9768). Stacking only images that increase the limiting magnitude yields: mean 1-sig. 1-sig. time sys. stat. since cal. cal. cal. trig. tel. exp. fil. magnitude stars* unc. unc. (# x s) (mag) (mag) 15.0 m PROMPT-4 2 x 80 R > 17.7 (3 sig.) 50 SDSS 7 0.008 0.010 15.0 m PROMPT-5 2 x 80 I > 17.0 (3 sig.) 20 SDSS 7 0.026 0.010 15.0 m PROMPT-2 2 x 80 V > 17.4 (3 sig.) 15 SDSS 7 0.030 0.020 32.1 m PROMPT-3 2 x 80 B > 18.5 (3 sig.) 25 SDSS 7 0.028 0.031 32.6 m PROMPT-2 4 x 80 V > 18.3 (3 sig.) 15 SDSS 7 0.039 0.010 + 1 x 40 32.7 m PROMPT-4 5 x 80 R > 18.4 (3 sig.) 50 SDSS 7 0.008 0.005 32.7 m PROMPT-5 5 x 80 I > 17.8 (3 sig.) 20 SDSS 7 0.026 0.005 62.0 m GORT 6 x 80 R > 18.8 (3 sig.) 34 SDSS 7 0.039 0.003 76.8 m GORT 9 x 80 I > 18.7 (3 sig.) 43 SDSS 7 0.097 0.003 117.3 m PROMPT-2 8 x 80 V > 18.7 (3 sig.) 17 SDSS 7 0.019 0.006 119.1 m PROMPT-4 11 x 80 R > 19.1 (3 sig.) 62 SDSS 7 0.229 0.003 119.2 m PROMPT-5 11 x 80 I > 18.4 (3 sig.) 25 SDSS 7 0.117 0.003 120.0 m PROMPT-3 10 x 80 B > 19.4 (3 sig.) 26 SDSS 7 0.085 0.011 3.2 h PROMPT-3 24 x 80 B > 21.3 (3 sig.) 26 SDSS 7 0.085 0.003 3.2 h GORT 16 x 80 I > 19.2 (3 sig.) 43 SDSS 7 0.097 0.002 3.4 h GORT 20 x 80 R > 20.0 (3 sig.) 34 SDSS 7 0.039 0.001 3.5 h PROMPT-2 67 x 80 V 21.05 +0.35 -0.27 17 SDSS 7 0.019 0.001 3.5 h PROMPT-5 66 x 80 I 20.60 +0.26 -0.21 25 SDSS 7 0.117 0.001 3.5 h PROMPT-4 65 x 80 R 21.35 +0.28 -0.22 62 SDSS 7 0.229 0.001 3.6 h PROMPT-3 37 x 80 U > 19.5 (3 sig.) 30 SDSS 7 0.015 0.012 * Transformed using Jester et al., 2005, ApJ, 130, 873.