Swift Observations of GRB 140909A

D. Palmer (), C. Pagani (U. Leicester) and M.H. Siegel (PSU) for the Swift team

1. Introduction

Palmer (GCN Circ. 16808) reported the initial Swift results. In two successive 64-second images, beginning at 06:56:51, BAT detected a source at a consistent location. 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

BAT results are not available.

3. XRT Observations and Analysis

We have analysed 12 ks of XRT data for the Swift/BAT-detected burst: GRB 140909A, from 44.0 ks to 251.9 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. The source is fading with α >0.8.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of GRB 140909A 44028 s after the BAT trigger (Siegel and Sonbas GCN Circ. 16812). No optical afterglow consistent with the XRT position (Pagani et al. GCN Circ. 16811) 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 E_B-V of 0.015 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

12^h54^m26.78^s +63°31'00.4" 7.2" XRT-final UKSSDC

12^h54^m26.78^s +63°31'00.4" 7.2" XRT Pagani et al. GCN Circ. 16811

12^h54^m33^s +63°29'38" BAT-initial Palmer GCN Circ. 16808

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Table 2. No GCN Circulars from other observatories were found.

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

white 44028 56310 3213 >22.0

RA (J2000)	Dec (J2000)	Error	Note	Reference
12^h54^m26.78^s	+63°31'00.4"	7.2"	XRT-final	UKSSDC
12^h54^m26.78^s	+63°31'00.4"	7.2"	XRT	Pagani et al. GCN Circ. 16811
12^h54^m33^s	+63°29'38"		BAT-initial	Palmer GCN Circ. 16808

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	44028	56310	3213	>22.0

Table 3. UVOT observation reported by Siegel and Sonbas (GCN Circ. 16812). 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.

May 22, 2015