Swift Observations of GRB 140529A

J.R. Cummings (NASA/UMBC), P.A. Evans (U. Leicester) and S.R. Oates (IAA-CSIC, MSSL-UCL) for the Swift team

1. Introduction

At 09:28:06 the IPN detected GRB 140529A (Cummings GCN Circ. 16340). Table 1 contains the best reported positions from Swift.

Table 2 is a summary of GCN Circulars about this GRB from observatories other than Swift.

2. BAT Observations and Analysis

The maskweighted lightcurve (Figure 1) shows a single FRED peak with an estimated T₉₀ of 4.5 ± 0.5 seconds.

The best fit to the spectrum from 15-150 keV is a powerlaw with an exponential cutoff. The photon index is 0.85 ± 0.35 with a cutoff energy of 75 ± 10 keV. The best simple powerlaw fit has a photon index of 1.66 ± 0.08. The total fluence from 15-150 keV in5.0 seconds was (2.2 ± 0.1) x 10^-6 ergs/cm². This fluence is larger than that of 62% of the long GRBs in the Second BAT GRB Catalog (Sakamoto et al. 2011). The 1-second peak flux in the energy range 15-150 keV was 11.5 ± 0.7 photons/cm².

3. XRT Observations and Analysis

We have analysed 2.5 ks of XRT data for the Swift/BAT-detected burst: GRB 140529A, from 65.0 ks to 75.4 ks after the Swift/BAT trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the Swift/BAT error circle. We cannot determine at the present time whether the source is fading.

The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020383.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of the ground-detected GRB 140529A 65ks after the BAT trigger (Cummings, GCN (Oates and Racusin GCN Circ. 16343). Circ. 16340). 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 0.13 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

15^h15^m07.67^s -41°03'10.9" 3.3" XRT-final UKSSDC

15^h15^m07.68^s -41°03'10.6" 3.3" XRT Evans and Racusin GCN Circ. 16342

15^h15^m14.4^s -41°02'33" 1.2' BAT-refined Cummings et al. GCN Circ. 16346

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Gamma-ray Golenetskii et al. 16345 Konus-Wind observation Konus-Wind E_peak=52 (-31,+17) keV
Fluence=2.6(-0.3,+0.3)x10^-6erg 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 65040 69412 287 >21.0

u 65017 74873 1635 >21.0

RA (J2000)	Dec (J2000)	Error	Note	Reference
15^h15^m07.67^s	-41°03'10.9"	3.3"	XRT-final	UKSSDC
15^h15^m07.68^s	-41°03'10.6"	3.3"	XRT	Evans and Racusin GCN Circ. 16342
15^h15^m14.4^s	-41°02'33"	1.2'	BAT-refined	Cummings et al. GCN Circ. 16346

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Gamma-ray	Golenetskii et al.	16345	Konus-Wind observation	Konus-Wind	E_peak=52 (-31,+17) keV Fluence=2.6(-0.3,+0.3)x10^-6erg cm^-2

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	65040	69412	287	>21.0
u	65017	74873	1635	>21.0

Table 3. UVOT observations reported by Oates and Racusin (GCN Circ. 16343). 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 31, 2014