[AAVSO-HEN] GRB 090812: Skynet/PROMPT and GORT Observations

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

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  <haislip at physics.unc.edu>

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.