Swift Observations of GRB 140311C

V. D'Elia (ASDC) for the Swift team

1. Introduction

Stanbro (GCN Circ. 15977) reported the GRB detection. At 14:49:13.10 UT on 11 March 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140311C (trigger 416242156/140311618). Table 1 contains the best reported positions from Swift.

Singer et al. (GCN Circ. 15971) reported the position from iPTF for the optical afterglow of this GRB. Table 2 is a summary of GCN Circulars about this GRB from observatories other than Swift.

2. BAT Observations and Analysis

BAT did not observe this burst.

3. XRT Observations and Analysis

XRT results are not available.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of GRB 140311C 118480 s after the trigger (D'Elia et al. GCN Circ. 15982). No optical afterglow consistent with the iPTF position (Singer et al., GCN Circ. 15971) is detected in the initial UVOT exposure. Table 3 gives preliminary magnitudes using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc., 1358, 373). No correction has been made for the expected extinction in the Milky Way corresponding to a reddening of EB-V of 0.01 mag. in the direction of the GRB (Schlegel et al. 1998).

Figure 1. The BAT light curve is not available.

RA (J2000) Dec (J2000) Error Note Reference

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Singer et al. 15971 Fermi416242156: possible iPTF
counterpart		 iPTF possible detection
Optical Yurkov et al. 15981 MASTER before, during and after trigger
optical observations 		MASTER upper limits
Optical Gorbovskoy et al. 15983 MASTER optical observations MASTER
Gamma-ray Stanbro 15977 Fermi GBM Detection Fermi GBM Epeak=56±6 keV
T90=14 seconds
Fluence=4.6±0.2x10-6erg cm-2
(55th percentile for long GRBs)

Table 2. Summary of GCN Circulars from other observatories sorted by band and then circular number.

Filter Tstart(s) Tstop(s) Exp(s) Mag
u 118480 125414 2916 >21.43

Table 3. UVOT observation reported by D'Elia et al. (GCN Circ. 15982). The start and stop time of the exposure are given in seconds since the BAT trigger. The preliminary 3-σ upper limit is given. No correction has been made for extinction in the Milky Way.

March 15, 2014