GALI Localization of Off-Grid GRB Directions: A Comparison of Rectangular and Triangular Calibration Meshes
Abstract
Rapid localization of gamma-ray bursts (GRBs) is essential for multi-wavelength and multi-messenger follow-up, but combining wide sky coverage with accurate localization remains challenging. GALI (GAmma-ray burst Localizing Instrument) determines source directions from count-rate modulations caused by internal shadowing in a three-dimensional scintillator array. We investigate a triangular calibration mesh based on an icosphere tessellation of the hemisphere and compare it with the rectangular mesh used previously. The triangular mesh samples the hemisphere more isotropically and gives better interpolation between calibration points. Laboratory measurements with the full-scale GALI detector yield an average angular separation of 0.86∘ ± 0.14∘ for random source directions, compared with 1.19∘ ± 0.28∘ for the rectangular mesh. Monte Carlo simulations of 50,000 randomly distributed GRBs in realistic low-Earth-orbit background conditions, each with 1000 detected counts, give average angular separations of 1.91∘ ± 1.20∘ and 2.73∘ ± 2.18∘ for triangular and rectangular meshes, respectively. The better laboratory performance is partly attributed to its approximately 3-4 times higher detected counts. Additional simulations indicate sensitivity from 10 keV to ∼1 MeV, with a peak effective area of about 130 cm2 near 100-150 keV. A compact 1U GALI implementation also achieves degree-scale localization in simulations, demonstrating the concept's potential for CubeSat-based GRB and multi-messenger missions.
Related
- Localizing binary neutron stars with the Einstein Telescope: a full Bayesian comparison of the triangular and 2L configurations
- State of the Art in Direct Dark Matter Detectors: Technologies, Performance, and Future Directions
- Juice/SWI during the Lunar-Earth-Gravity-Assist (LEGA) – Part 3: Observations of the Earth as calibration target
- Machine Learning Sensor Fusion for Water Vapor Radiometry based Tropospheric Delay Calibration
- Updates to STIS NUV Dark Calibration
BibTeX
@misc{salehnatur2026gali,
title = {{GALI Localization of Off-Grid GRB Directions: A Comparison of Rectangular and Triangular Calibration Meshes}},
author = {Julia Saleh-Natur and Ehud Behar and Omer Reich and Shlomit Tarem and Zvika Tarem and Alex Vdovin and Amir Feigenboim and Roey Evental and Solomon Margolin},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.07763},
eprint = {2611.07763},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.07763},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - GALI Localization of Off-Grid GRB Directions: A Comparison of Rectangular and Triangular Calibration Meshes
AU - Julia Saleh-Natur
AU - Ehud Behar
AU - Omer Reich
AU - Shlomit Tarem
AU - Zvika Tarem
AU - Alex Vdovin
AU - Amir Feigenboim
AU - Roey Evental
AU - Solomon Margolin
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.07763
UR - https://arxiv.org/abs/2611.07763
AB - Rapid localization of gamma-ray bursts (GRBs) is essential for multi-wavelength and multi-messenger follow-up, but combining wide sky coverage with accurate localization remains challenging. GALI (GAmma-ray burst Localizing Instrument) determines source directions from count-rate modulations caused by internal shadowing in a three-dimensional scintillator array. We investigate a triangular calibration mesh based on an icosphere tessellation of the hemisphere and compare it with the rectangular mesh used previously. The triangular mesh samples the hemisphere more isotropically and gives better interpolation between calibration points. Laboratory measurements with the full-scale GALI detector yield an average angular separation of 0.86^∘ ± 0.14^∘ for random source directions, compared with 1.19^∘ ± 0.28^∘ for the rectangular mesh. Monte Carlo simulations of 50,000 randomly distributed GRBs in realistic low-Earth-orbit background conditions, each with 1000 detected counts, give average angular separations of 1.91^∘ ± 1.20^∘ and 2.73^∘ ± 2.18^∘ for triangular and rectangular meshes, respectively. The better laboratory performance is partly attributed to its approximately 3-4 times higher detected counts. Additional simulations indicate sensitivity from 10 keV to ∼1 MeV, with a peak effective area of about 130 cm^2 near 100-150 keV. A compact 1U GALI implementation also achieves degree-scale localization in simulations, demonstrating the concept's potential for CubeSat-based GRB and multi-messenger missions.
ER -