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arXiv · 2110.00576

A clock stabilization system for CHIME/FRB Outriggers

J. Mena-Parra·C. Leung·S. Cary·K. W. Masui·J. F. Kaczmarek·M. Amiri·K. Bandura·P. J. Boyle·T. Cassanelli·J. -F. Cliche·M. Dobbs·V. M. Kaspi·T. L. Landecker·A. Lanman·J. L. Sievers
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Abstract

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has emerged as the prime telescope for detecting fast radio bursts (FRBs). CHIME/FRB Outriggers will be a dedicated very-long-baseline interferometry (VLBI) instrument consisting of outrigger telescopes at continental baselines working with CHIME and its specialized real-time transient-search backend (CHIME/FRB) to detect and localize FRBs with 50 mas precision. In this paper we present a minimally invasive clock stabilization system that effectively transfers the CHIME digital backend reference clock from its original GPS-disciplined ovenized crystal oscillator to a passive hydrogen maser. This enables us to combine the long-term stability and absolute time tagging of the GPS clock with the short and intermediate-term stability of the maser to reduce the clock timing errors between VLBI calibration observations. We validate the system with VLBI-style observations of Cygnus A over a 400 m baseline between CHIME and the CHIME Pathfinder, demonstrating agreement between sky-based and maser-based timing measurements at the 30 ps rms level on timescales ranging from one minute to up to nine days, and meeting the stability requirements for CHIME/FRB Outriggers. In addition, we present an alternate reference clock solution for outrigger stations which lack the infrastructure to support a passive hydrogen maser.

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J. Mena-Parra, C. Leung, S. Cary, K. W. Masui, J. F. Kaczmarek, M. Amiri, K. Bandura, P. J. Boyle, T. Cassanelli, J. -F. Cliche, M. Dobbs, V. M. Kaspi, T. L. Landecker, A. Lanman, J. L. Sievers. 2021-10-01. A clock stabilization system for CHIME/FRB Outriggers. https://doi.org/10.3847/1538-3881%2Fac397a

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