Swift Observations of GRB 160509A

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

1. Introduction

Longo et al. (GCN Circ. 19403) reported the GRB detection. At 08:59:04.36 UTC on May 09, 2016, Fermi-LAT triggered on high-energy emission from GRB 160509A, also detected by GBM (trigger 484477130/160509374). Table 1 contains the best reported positions from Swift.

Levan et al. (GCN Circ. 19410) reported the position from Gemini for the optical afterglow of this GRB. Tanvir et al. (GCN Circ. 19419) determined a redshift of 1.17 from Gemini. 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 Roegiers GCN Circ. 19412) of the Swift-XRT afterglow (Kennea et al., GCN Circ. 19408) 7259 s after the LAT trigger (Longo et al., GCN Circ. 19403). No UVOT source consistent with the position of Swift-XRT afterglow or the position of the optical afterglow candidate (Levan et al., GCN Circ. 19410) is found in the initial 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 0.31 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
20h47m00.90s +76°06'30.1" 2.3" XRT Kennea et al. GCN Circ. 19408

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Izzo et al. 19409 optical observations iTelescope
Optical Levan et al. 19410 Gemini North candidate afterglow Gemini detection
Optical Cenko et al. 19416 DCT Imaging / Afterglow Confirmation Discovery Channel detection
Optical Tanvir et al. 19419 Gemini North redshift Gemini redshift
Optical Schmidl et al. 19421 TLS Tautenburg Afterglow Detection Tautenburg detection
Optical Yurkov et al. 19425 MASTER-NET observations MASTER
Radio Alexander et al. 19414 VLA Detection VLA detection
Radio Cenko et al. 19428 Further VLA Observations VLA
X-ray Ono et al. 19405 Correction to GCN Circ. 19404; GRB 160509A:
MAXI/GSC detection 		MAXI detection
X-ray Negoro et al. 19415 MAXI/GSC refined analysis MAXI
Gamma-ray Longo et al. 19403 Fermi-LAT prompt detection of a very
bright burst		 Fermi LAT
Gamma-ray Roberts et al. 19411 Fermi GBM Detection Fermi GBM Epeak=370±7 keV
T90=371 seconds
Fluence=1.51±0.01x10-4erg cm-2
(98.7 percentile for long GRBs)
Gamma-ray Longo et al. 19413 Fermi-LAT refined analysis Fermi LAT Emax=52 GeV
Gamma-ray Frederiks et al. 19417 Konus-Wind observation Konus-Wind Epeak=288 (-45,+48) keV
Fluence=2.90(-0.35,+0.35)x10-4erg cm-2
Gamma-ray Lennarz and Taboada 19423 non-observation of VHE emission with
HAWC		 HAWC
Gamma-ray Yoshida et al. 19424 CALET Gamma-Ray Burst Monitor detection CALET

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 7259 19794 626 >21.6
u 24201 36310 1802 >22.2
v 25452 36990 1257 >21.4
white 24826 36919 1802 >23.2

Table 3. UVOT observations reported by Marshall and Roegiers (GCN Circ. 19420). 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.

June 15, 2016