Paper
Long-Integration Magnetar Burst Observatory (LIMBO): Instrument Summary and Early FRB Rate Constraints
Authors
Darby McCauley, Aaron Parsons, Wei Liu, Wenbin Lu, Dirk Wright, Dan Werthimer
Abstract
The Long-Integration Magnetar Burst Observatory (LIMBO) is a real-time radio transient detection pipeline designed to search for dispersed fast radio bursts (FRBs) from Galactic magnetars. Deployed at the University of California, Berkeley's Leuschner Radio Observatory, LIMBO employs a $4.3~\mathrm{m}$ dish with a dual-polarization feed to continuously monitor a $250~\mathrm{MHz}$ band centred at $1475~\mathrm{MHz}$. A real-time processing pipeline performs a search for dispersed transients on the summed polarizations, with detections triggering dumps of buffered voltage data to disk. Based on calibrated sensitivity measurements, synthetic signal-injection and recovery tests, and successful detection of pulses from the Crab Pulsar, we determine that LIMBO is sensitive to radio transients with fluences $\geq 43~\mathrm{Jy \cdot ms}$. Between May and August 2023, LIMBO conducted 833 hours of follow-up observations of the Galactic magnetar SGR 1935+2154, yielding 12 candidate FRB detections. If these events are true, we measure FRB-like event rates from SGR 1935+2154 of $R(\geq 65~\mathrm{Jy \cdot ms}) = 112.3^{+81.3}_{-54.5}~\mathrm{yr}^{-1}$ and $R(\geq 130~\mathrm{Jy \cdot ms}) = 17.7^{+40.8}_{-15.1}~\mathrm{yr}^{-1}$. Combining these results with previously reported FRBs from SGR 1935+2154, we infer a cumulative rate-fluence power-law slope of $α=-0.60^{+0.24}_{-0.28}$ in the fluence range between $10$ and $10^6\rm\, Jy \cdot ms$. These observations demonstrate the capability of continuous, real-time monitoring of Galactic magnetars and establish LIMBO as an effective instrument for detecting Galactic FRBs.
Metadata
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"raw_xml": "<entry>\n <id>http://arxiv.org/abs/2603.05603v1</id>\n <title>Long-Integration Magnetar Burst Observatory (LIMBO): Instrument Summary and Early FRB Rate Constraints</title>\n <updated>2026-03-05T19:01:47Z</updated>\n <link href='https://arxiv.org/abs/2603.05603v1' rel='alternate' type='text/html'/>\n <link href='https://arxiv.org/pdf/2603.05603v1' rel='related' title='pdf' type='application/pdf'/>\n <summary>The Long-Integration Magnetar Burst Observatory (LIMBO) is a real-time radio transient detection pipeline designed to search for dispersed fast radio bursts (FRBs) from Galactic magnetars. Deployed at the University of California, Berkeley's Leuschner Radio Observatory, LIMBO employs a $4.3~\\mathrm{m}$ dish with a dual-polarization feed to continuously monitor a $250~\\mathrm{MHz}$ band centred at $1475~\\mathrm{MHz}$. A real-time processing pipeline performs a search for dispersed transients on the summed polarizations, with detections triggering dumps of buffered voltage data to disk. Based on calibrated sensitivity measurements, synthetic signal-injection and recovery tests, and successful detection of pulses from the Crab Pulsar, we determine that LIMBO is sensitive to radio transients with fluences $\\geq 43~\\mathrm{Jy \\cdot ms}$. Between May and August 2023, LIMBO conducted 833 hours of follow-up observations of the Galactic magnetar SGR 1935+2154, yielding 12 candidate FRB detections. If these events are true, we measure FRB-like event rates from SGR 1935+2154 of $R(\\geq 65~\\mathrm{Jy \\cdot ms}) = 112.3^{+81.3}_{-54.5}~\\mathrm{yr}^{-1}$ and $R(\\geq 130~\\mathrm{Jy \\cdot ms}) = 17.7^{+40.8}_{-15.1}~\\mathrm{yr}^{-1}$. Combining these results with previously reported FRBs from SGR 1935+2154, we infer a cumulative rate-fluence power-law slope of $α=-0.60^{+0.24}_{-0.28}$ in the fluence range between $10$ and $10^6\\rm\\, Jy \\cdot ms$. These observations demonstrate the capability of continuous, real-time monitoring of Galactic magnetars and establish LIMBO as an effective instrument for detecting Galactic FRBs.</summary>\n <category scheme='http://arxiv.org/schemas/atom' term='astro-ph.IM'/>\n <category scheme='http://arxiv.org/schemas/atom' term='astro-ph.HE'/>\n <published>2026-03-05T19:01:47Z</published>\n <arxiv:comment>16 pages, 15 figures, submitting to RASTI</arxiv:comment>\n <arxiv:primary_category term='astro-ph.IM'/>\n <author>\n <name>Darby McCauley</name>\n </author>\n <author>\n <name>Aaron Parsons</name>\n </author>\n <author>\n <name>Wei Liu</name>\n </author>\n <author>\n <name>Wenbin Lu</name>\n </author>\n <author>\n <name>Dirk Wright</name>\n </author>\n <author>\n <name>Dan Werthimer</name>\n </author>\n </entry>"
}