GCN Circular 17605
Subject
GRB 150318A: Skynet PROMPT-CTIO Observations
Date
2015-03-18T18:23:19Z (9 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, D. Reichart, J. Haislip, A. Aji, R. Beauchemin, T. Berger, A. Dow, A. Foster,
N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. Maples, J. Moore, M. Nysewander, C. Salemi,
L. Zbinden, and J. A. Crain report:
Skynet observed the Swift BAT/XRT localization of GRB 150318A (Pagani et al., GCN 17599, Swift
trigger=635289) with with one 24" telescope (PROMPT 8; I band) and four 16" telescopes
(PROMPT 1,3,4,5; V,B,R,I bands) of the PROMPT array at CTIO, Chile.
Starting at 2015-03-18 06:06:54 UT and continuing until 09:52 UT (t=2m-2.8h post-trigger),
Skynet took a total of 376 exposures ranging from 10-160s. We stacked subsets of these images
to maximize the S/N ratio, and detected no optical source in any band at the XRT position.
Our 3-sigma limiting magnitudes are:
==============================================
tmid scope band exposures lim mag
----------------------------------------------
104m PROMPT8 I 69 x 80s >20.9
104m PROMPT5 I 43 x 160s >20.9
78m PROMPT4 R 37 x 80s >20.9
104m PROMPT1 V 42 x 160s >21.6
125m PROMPT3 B 18 x 160s >21.1
Limiting magnitudes are in the Vega System, calibrated to 3 APASS stars in the field. Magnitudes
have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.03
(Schlafly & Finkbeiner 2011).
No further Skynet observations are scheduled.