TITLE:   GCN CIRCULAR
NUMBER:  12544
SUBJECT: Continued Skynet observations of GRB111107A
DATE:    11/11/07 22:21:48 GMT
FROM:    Aaron LaCluyze at U.North Carolina  <lacluyze@email.unc.edu>

A. LaCluyze, J. Haislip, K. Ivarsen, D. Reichart, M. Nysewander, J. Moore, 
A. Trotter, R. Egger, A. Foster, A. Oza, T. Cromartie, E. Speckhard, and J. 
A. Crain report:

Skynet continued observing the field of GRB 111107A (Swift trigger 507185, 
Siegel et al., GCN 12534; LaCluyze et al., GCN 12535; Kruehler et al., GCN 
12536; Kuin et al., GCN 12540) with the PROMPT telescopes located at CTIO 
in Chile in B, R, and I.  We detect the fading optical counterpart in R and 
I, with limits in B.  The fading is consistent with a power-law index of 
~-0.7.

Preliminary light curve can be found at the following link:
http://skynet.unc.edu/grb/grb111107a.png


Prompt4, R-band, calibrated to 12 USNO B1.0 stars

T(mean) Tmean(days) Exps     Mag     1-sig MagErr
14.75 m  0.01024  5 x 80 s   19.467  +0.427/-0.311
30.93 m  0.02148  13 x 80 s  19.883  +0.360/-0.273
61.87 m  0.04296  24 x 80 s  20.319  +0.337/-0.259
118.57 m 0.08234  43 x 80 s  20.818  +0.404/-0.298
3.815 h  0.15895  94 x 80 s  21.206  +0.243/-0.200
6.619 h  0.27579  102 x 80 s 21.837  +0.357/-0.271


Prompt5, I-band, calibrated to 15 USNO B1.0 stars

T(mean) Tmean(days) Exps     Mag     1-sig MagErr
15.22 m  0.01057  4 x 80 s   18.443  +0.274/-0.220
24.77 m  0.01720  5 x 80 s   18.520  +0.263/-0.212
49.60 m  0.03444  24 x 80 s  19.474  +0.262/-0.212
112.45 m 0.07809  49 x 80 s  19.898  +0.300/-0.237
3.139 h  0.13081  43 x 80 s  20.297  +0.390/-0.291
6.189 h  0.25788  130 x 80 s 20.650  +0.273/-0.220


Prompt3, B-band, calibrated to 14 USNO B1.0 stars

T(mean) Tmean(days) Exps   3-SigLimMag
88.62 m  0.06154  47 x 80 s  20.3
4.738 h  0.19743  159 x 80 s 21.6


Further observations are planned.  This message may be cited.