Swift Observations of GRB 151122A

D. Palmer (), A. Melandri (INAF-OAB) and M.H. Siegel (PSU) for the Swift team

1. Introduction

Palmer (GCN Circ. 18637) reported the initial Swift results. On November 22, at 17:00:40 UT, BAT rate-triggered and detected a 6.0 sigma peak in an image. 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.

Standard analysis products for this burst are available at http://gcn.gsfc.nasa.gov/swift_gnd_ana.html.

2. BAT Observations and Analysis

BAT results are not available.

3. XRT Observations and Analysis

XRT results are not available.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of GRB 151122A 102884 s after the BAT trigger (Siegel and Evans GCN Circ. 18641). No optical afterglow consistent with either of the XRT positions given by Evans et al. (GCN Circ. 18640) 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 0.20 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

19^h58^m49^s -19°53'56" 3' BAT-initial Palmer GCN Circ. 18637

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Gamma-ray Stanbro 18639 Fermi GBM detection Fermi GBM T₉₀=30 seconds
Fluence=2.18±0.15x10^-6erg cm^-2
(31^st percentile for long GRBs)

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

w2 102884 113997 2933 >21.1

RA (J2000)	Dec (J2000)	Error	Note	Reference
19^h58^m49^s	-19°53'56"	3'	BAT-initial	Palmer GCN Circ. 18637

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Gamma-ray	Stanbro	18639	Fermi GBM detection	Fermi GBM	T₉₀=30 seconds Fluence=2.18±0.15x10^-6erg cm^-2 (31^st percentile for long GRBs)

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
w2	102884	113997	2933	>21.1

Table 3. UVOT observation reported by Siegel and Evans (GCN Circ. 18641). 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.

November 29, 2015