Swift Observations of GRB 140320C

C. Pagani (U. Leicester) and S.R. Oates (UCL-MSSL) for the Swift team

1. Introduction

Mereghetti et al. (GCN Circ. 16007) reported the GRB detection. A gamma ray burst lasting about 30 s has been detected by IBAS in the IBIS/ISGRI data at 13:17:20 UT of March 20, 2014. Table 1 contains the best reported positions from Swift.

Volnova et al. (GCN Circ. 16036) reported the position from Mondy 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

We have analysed 4.0 ks of XRT data for the INTEGRAL-detected burst: GRB 140320C, from 19.5 ks to 37.3 ks after the INTEGRAL trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the INTEGRAL error circle.

The light curve (Figure 2) can be modelled with a power-law decay with a decay index of α=2.8 (+1.0, -1.7).

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations (Oates and Cannizzo GCN Circ. 16021) of the field of GRB 140320C 19435 s after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 16007). No optical afterglow consistent with the XRT position (Pagani et al., GCN Circ. 16015; 16017) is detected in the initial UVOT exposures. 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 E_B-V of 0.07 mag. in the direction of the GRB (Schlegel et al. 1998).

Figure 1. The BAT light curve is not available.

XRT light curve

Figure 2. The XRT light curve. Any data from a crosshatched region are not included in the fit.

RA (J2000) Dec (J2000) Error Note Reference

08^h57^m34.61^s +71°11'54.2" 2.6" XRT-final UKSSDC

08^h57^m34.61^s +71°11'54.2" 2.6" XRT Pagani GCN Circ. 16017

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Melandri et al. 16008 FTN optical observations FTN

Optical Yurkov et al. 16009 MASTER optical observations MASTER

Optical Volnova et al. 16012 Mondy optical observations Mondy

Optical Wei et al. 16022 Mini-GWAC prompt observation Xinglong Obs.

Optical Volnova et al. 16036 Mondy optical observations and
afterglow confirmation Mondy detection

Gamma-ray Mereghetti et al. 16007 A long GRB detected by INTEGRAL INTEGRAL Fluence=2x10^-7erg cm^-2

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

Filter T_start(s) T_stop(s) Exp(s) Mag

white 20211 32984 1056 >22.1

v 20986 33302 1087 >20.5

u 19435 37277 1741 >21.4

RA (J2000)	Dec (J2000)	Error	Note	Reference
08^h57^m34.61^s	+71°11'54.2"	2.6"	XRT-final	UKSSDC
08^h57^m34.61^s	+71°11'54.2"	2.6"	XRT	Pagani GCN Circ. 16017

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Melandri et al.	16008	FTN optical observations	FTN
Optical	Yurkov et al.	16009	MASTER optical observations	MASTER
Optical	Volnova et al.	16012	Mondy optical observations	Mondy
Optical	Wei et al.	16022	Mini-GWAC prompt observation	Xinglong Obs.
Optical	Volnova et al.	16036	Mondy optical observations and afterglow confirmation	Mondy	detection
Gamma-ray	Mereghetti et al.	16007	A long GRB detected by INTEGRAL	INTEGRAL	Fluence=2x10^-7erg cm^-2

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	20211	32984	1056	>22.1
v	20986	33302	1087	>20.5
u	19435	37277	1741	>21.4

Table 3. UVOT observations reported by Oates and Cannizzo (GCN Circ. 16021). The start and stop times of the exposures are given in seconds since the BAT trigger. The preliminary 3-σ upper limits are given. No correction has been made for extinction in the Milky Way.

May 22, 2015