GCN Circular 34208
Subject
IceCube-230708A: Upper limits from Swift/BAT-GUANO
Event
Date
2023-07-13T03:09:49Z (3 years ago)
From
Samuele Ronchini at PSU <sjs8171@psu.edu>
Samuele Ronchini (PSU), Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), James DeLaunay (U Alabama), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
The neutrino candidate (GCN 34203) was inside the coded BAT field of view.
The IceCube notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, considering IceCube localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-8 erg/s/cm^2:
Bin duration (s) | hard normal soft GRB 170817A
----------------------------------------------------
0.256 | 10.4 15.0 13.8 15.9
1.024 | 5.3 7.7 7.1 8.1
4.096 | 2.9 4.2 3.8 4.4
16.384 | 1.8 2.6 2.4 2.8
The upper limits as function of sky position are plotted here:
https://doi.org/10.5281/zenodo.8141103
The corresponding fits file can be found here:
https://doi.org/10.5281/zenodo.8140900
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/