Swift Observations of GRB 150514A

J.A. Kennea (PSU) and F.E. Marshall (NASA/GSFC) for the Swift team

1. Introduction

Kocevski and Arimoto (GCN Circ. 17816) reported the GRB detection. At 18:35:05.35 on May 14, 2015, Fermi-LAT detected high-energy emission from GRB 150514A, which was also detected by Fermi-GBM (trigger 453321308). Table 1 contains the best reported positions from Swift.

Marshall and Cannizzo (GCN Circ. 17820) reported the detection with UVOT of an optical afterglow. de Ugarte Postigo et al. (GCN Circ. 17822) determined a redshift of 0.807 from VLT. 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 (Marshall and Cannizzo GCN Circ. 17820) of the field of GRB 150514A 40750 s after the LAT trigger (Kocevski and Arimoto, GCN Circ. 17816). A source consistent with the XRT position (Kennea et al. GCN Circ. 17818) 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 0.02 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

04^h59^m30.30^s -60°58'06.3" 0.43" UVOT-refined Marshall and Cannizzo GCN Circ. 17820

04^h59^m30.46^s -60°58'06.9" 2.0" XRT-final UKSSDC

04^h59^m30.00^s -60°58'08.8" 3.9" XRT Kennea et al. GCN Circ. 17818

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Yates et al. 17821 GROND Bright Afterglow Confirmation GROND detection

Optical de Ugarte Postigo et al. 17822 VLT/X-shooter redshift VLT redshift

Gamma-ray Kocevski and Arimoto 17816 Fermi-LAT detection Fermi LAT

Gamma-ray Roberts et al. 17819 Fermi GBM Detection Fermi GBM E_peak=73±6 keV
T₉₀=10.8 seconds
Fluence=4.9±0.2x10^-6erg cm^-2
(56^th percentile for long GRBs)

Gamma-ray Golenetskii et al. 17823 Konus-Wind observation Konus-Wind E_peak=60 (-14,+10) keV
Fluence=3.7(-0.7,+0.7)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 41402 41850 440 18.60 ± 0.04

v 42049 42222 170 18.71 ± 0.20

u 40750 41396 636 18.20 ± 0.05

RA (J2000)	Dec (J2000)	Error	Note	Reference
04^h59^m30.30^s	-60°58'06.3"	0.43"	UVOT-refined	Marshall and Cannizzo GCN Circ. 17820
04^h59^m30.46^s	-60°58'06.9"	2.0"	XRT-final	UKSSDC
04^h59^m30.00^s	-60°58'08.8"	3.9"	XRT	Kennea et al. GCN Circ. 17818

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Yates et al.	17821	GROND Bright Afterglow Confirmation	GROND	detection
Optical	de Ugarte Postigo et al.	17822	VLT/X-shooter redshift	VLT	redshift
Gamma-ray	Kocevski and Arimoto	17816	Fermi-LAT detection	Fermi LAT
Gamma-ray	Roberts et al.	17819	Fermi GBM Detection	Fermi GBM	E_peak=73±6 keV T₉₀=10.8 seconds Fluence=4.9±0.2x10^-6erg cm^-2 (56^th percentile for long GRBs)
Gamma-ray	Golenetskii et al.	17823	Konus-Wind observation	Konus-Wind	E_peak=60 (-14,+10) keV Fluence=3.7(-0.7,+0.7)x10^-6erg cm^-2

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	41402	41850	440	18.60 ± 0.04
v	42049	42222	170	18.71 ± 0.20
u	40750	41396	636	18.20 ± 0.05

Table 3. UVOT observations reported by Marshall and Cannizzo (GCN Circ. 17820). The start and stop times of the exposures are given in seconds since the BAT trigger. The preliminary detections and 3-σ upper limits are given. No correction has been made for extinction in the Milky Way.

May 19, 2015