IceCube-230708A: Upper limits from Swift/BAT-GUANO

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/