[vsnet-grb-info 14544] GRB 140215A: Continued Skynet PROMPT Observations of the Optical Afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15858
SUBJECT: GRB 140215A: Continued Skynet PROMPT Observations of the Optical Afterglow
DATE:    14/02/18 15:48:45 GMT
FROM:    Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet  <atrotter at physics.unc.edu>

A. LaCluyze, J. Haislip, D. Reichart, A. Trotter, S. Poshyachinda, W. 
Rujopakarn, A. Foster, N. Frank, K. Ivarsen, J. Moore, M. Nysewander, R. 
Beauchemin, T. Berger, M. Carroll, H. T. Cromartie, R. Egger, M. 
Hinckle, A. Ireland, M. Maples, L. Scott, and J. A. Crain report:

Skynet continued observing the Swift-BAT localization of GRB 140215A 
(Markwardt et al., GCN 15837, Swift trigger 586680) with six of the 
PROMPT telescopes located at CTIO in Chile.  LaCluyze et al. (GCN 15840) 
described rapid-response observations of a fading optical afterglow 
taken between ~1m and 6.5m after the burst in BVRI and luminance, and 
presented a preliminary light curve calibrated to USNOB and NOMAD 
catalog stars. A revised and recalibrated light curve, including 
observations taken at t~20-24h, is at:

http://www.skynet.unc.edu/grb/grb140215a_2.png

In stacks of ~45x160s images from the second night, we do not detect the 
afterglow with any degree of confidence (the I-band "detections" in the 
light curve plot are most likely spurious.) The 3-sigma limiting 
magnitudes are:

Band      tmid      Limit
I         21.9h     >20.2
R         21.0h     >20.5
V         21.8h     >20.5
B         21.7h     >20.3

Magnitudes are in the Vega system, and were calibrated to 4 APASS DR7 
catalog stars in the field. They have not been corrected for 
line-of-sight MW dust extinction corresponding to E(B-V)=0.09 (Schlegel 
et al. 1998).

No further Skynet observations are scheduled.