Swift Observations of GRB 131122A

A. Maselli (INAF-IASFPA) and C.A. Swenson (PSU) for the Swift team

1. Introduction

Gotz et al. (GCN Circ. 15510) reported the GRB detection. a gamma ray burst lasting about 70 s has been detected by IBAS in the IBIS/ISGRI data at 21:25:01 U.T. 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 7.9 ks of XRT data for the INTEGRAL-detected burst: GRB 131122A, from 13.7 ks to 689.7 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 source has a mean count rate of 2.3 x 10-3 ct s-1; we cannot determine at the present time whether it is fading.

The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020328.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of GRB 131122A 13578 s after the INTEGRAL trigger (Gotz et al., GCN Circ. 15510) (Swenson and Maselli GCN Circ. 15515). No optical counterpart consistent with the potential XRT afterglow position (Maselli et al., GCN Circ. 15513) 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 EB-V of 0.01 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 cross-hatched region are not included in the fit.

RA (J2000) Dec (J2000) Error Note Reference
10h10m10.12s +57°43'39.7" 4.8" XRT-final UKSSDC
10h10m10.12s +57°43'39.7" 4.8" XRT Maselli and D'Elia GCN Circ. 15513

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Gorbovskoy et al. 15509 (INTEGRAL trigger N6392): MASTER-NET
optical observation		 MASTER upper limits
Optical Xu et al. 15511 Nanshan optical upper limit Xinjiang Astro.Obs. upper limits
Optical Gorosabel et al. 15512 i-band observations from NOT NOT
Optical de Ugarte Postigo et al. 15514 Upper limit from NOT imaging NOT upper limits
Gamma-ray Gotz et al. 15510 a long GRB detected with INTEGRAL INTEGRAL detection

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

Filter Tstart(s) Tstop(s) Exp(s) Mag
white 14302 20578 855 >21.3
v 20830 21061 227 >19.0
u 13578 20136 1375 >21.0

Table 3. UVOT observations reported by Swenson and Maselli (GCN Circ. 15515). 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.


December 2, 2013