Swift Observations of GRB 221231A

M. Perri (SSDC and INAF-OAR) for the Swift team

1. Introduction

A. Tohuvavohu (GCN Circ. 33132) reported the GRB detection. 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 refined results are not available.

3. XRT Observations and Analysis

Analysis of the initial XRT data was reported by Perri et al. (GCN Circ. 33139). Of the sources reported by Perri et al. (GCN Circ. 33135), "Source 2" is fading with >3-sigma significance, and is therefore likely the GRB afterglow.

The light curve (Figure 2) can be modelled with a power-law decay with a decay index of α=1.1 (+0.6, -0.5).

4. UVOT Observations and Analysis

UVOT results are not available.

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
22h25m01.44s +25°07'47.2" 3.1" XRT-final UKSSDC
22h25m01.44s +25°07'47.2" 3.0" XRT Perri et al. GCN Circ. 33139
22h25m02.47s +25°08'18.6" 5' BAT-GUANO A. Tohuvavohu GCN Circ. 33132

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical M. Odeh 33136 AKO Upper Limit Al-Khatim Obs. upper limits
Optical Ror et al. 33149 3.6m DOT optical upper limit DOT upper limits
Gamma-ray Fermi 33129 Fermi GBM Final Real-time Localization Fermi GBM
Gamma-ray Lesage and Meegan 33146 Fermi GBM Observation Fermi GBM Epeak=200±40 keV
T90=5 seconds
Fluence=4.4±0.4x10-7erg cm-2
(brighter than 4.2% of long GRBs)

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

January 5, 2023