[AAVSO-HEN] GRB 090531A: Skynet/PROMPT 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:  10016
SUBJECT: GRB 090531A: Skynet/PROMPT Observations
DATE:    09/10/11 21:32:42 GMT
FROM:    Aaron LaCluyze at U.North Carolina  <lacluyze at physics.unc.edu>

A. LaCluyze, D. Reichart, J. Haislip, K. Ivarsen, 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 090531A (Stamatikos et 
al., GCN 9454) with three of the 16" PROMPT telescopes at CTIO beginning 
6.1 minutes after the trigger in UVRI.

We do not detect the afterglow (Sbarufatti & Mangano, GCN 9525).  Stacking 
only images that increase the limiting magnitude yields:

mean                                                1-sig.  1-sig.
time                             3-sig.             sys.    stat.
since                            lim.    cal.       cal.    cal.
trig.  tel.      exp.      fil.  mag.    stars*     unc.    unc.
(m)              (# x s)                            (mag)   (mag)

6.5    PROMPT-5  1 x 40    I     17.6    32 SDSS 7  0.055   0.002
15.3   PROMPT-5  11 x 80   I     19.4    32 SDSS 7  0.055   0.000
84.0   PROMPT-3  75 x 80   U     19.3    7 SDSS 7   0.037   0.001
92.6   PROMPT-5  85 x 80   I     20.5    32 SDSS 7  0.055   0.000
                  + 1 x 40
94.1   PROMPT-4  43 x 80   V     21.1    37 SDSS 7  0.007   0.000
104.8  PROMPT-4  54 x 80   R     21.3    40 SDSS 7  0.018   0.000

* Transformed using Jester et al., 2005, ApJ, 130, 873.