Swift Observations of GRB 180718A

D. Svinkin (Ioffe Inst.) and J.P. Osborne (U. Leicester) for the Swift team

1. Introduction

Svinkin et al. (GCN Circ. 22959) reported the initial Swift results. Y. Lien, D. Palmer, S. Barthelmy, J. Cummings, and H. Krimm, on behalf of the Swift-BAT team, 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

The BAT mask-weighted light curve (Figure 1) shows a single-pulse structure that starts at ~T0 and ends at ~T+0.1 s. T90 (15-350 keV) is 0.08 ± 0.02 s (estimated error including systematics).

Due to the weakness of this burst, the BAT spectrum is not well-constrained. However, the burst seems to be relatively soft comparing to regular short GRBs.

3. XRT Observations and Analysis

Analysis of the initial XRT data was reported by Osborne et al. (GCN Circ. 23030).

4. UVOT Observations and Analysis

UVOT results are not available.

Figure 1. The BAT light curve is not available.

RA (J2000) Dec (J2000) Error Note Reference
22h24m04.6s +02°47'23.3" 3.0' BAT-initial Svinkin et al. GCN Circ. 22959

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Vlasenko et al. 22972 MASTER optical observation MASTER
Radio Bright et al. 23216 15 GHz upper limits from the AMI Short
GRB Program		 AMI upper limits
Gamma-ray Svinkin et al. 22959 short GRB detected by IPN and found in
ground analysis of BAT data		 IPN
Gamma-ray Hamburg et al. 22960 Fermi GBM detection Fermi GBM Epeak=187±61 keV
T90=0.08 seconds
Fluence=2.3±0.3x10-7erg cm-2
(34th percentile for short GRBs)

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

September 11, 2018