Timing Calibration of the NuSTAR X-Ray Telescope
Abstract
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission is the first focusing X-ray telescope in the hard X-ray (3–79 keV) band. Among the phenomena that can be studied in this energy band, some require high time resolution and stability: rotation-powered and accreting millisecond pulsars, fast variability from black holes and neutron stars, X-ray bursts, and more. Moreover, a good alignment of the timestamps of X-ray photons to UTC is key for multi-instrument studies of fast astrophysical processes. In this paper, we describe the timing calibration of the NuSTAR mission. In particular, we present a method to correct the temperature-dependent frequency response of the on-board temperature-compensated crystal oscillator. Together with measurements of the spacecraft clock offsets obtained during downlinks passes, this allows a precise characterization of the behavior of the oscillator. The calibrated NuSTAR event timestamps for a typical observation are shown to be accurate to a precision of ~65 μs.
Additional Information
© 2021 The American Astronomical Society. Received 2020 September 16; revised 2020 November 27; accepted 2020 December 7; published 2021 February 23. M.B. thanks the Fulbright Visiting Scholar Program for supporting a 9 month visit at Caltech. D.J.W. acknowledges financial support from STFC via an Ernest Rutherford fellowship. The authors wish to thank the NuSTAR X-ray Binaries WG, the Magnetars/RPP WG, and the Timing WG, for the hard work and fruitful discussions that led to, and improved, this work; Victoria Kaspi, Jill Burnham, Alessandro Riggio, Andrea Sanna, Paul Ray, Iulia Deneva, Franco Buffa and Alessio Trois for insightful discussions and suggestions. They also wish to thank the referee for their comments, that helped improving the quality of this paper. This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC. Facilities: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, NICER - , HEASARC - . Software: Nustar Clock Utils,15 Stingray (Huppenkothen et al. 2016, 2019), HENDRICS (Bachetti 2018), astropy (Price-Whelan et al. 2018), PINT (Luo et al. 2019), HEASoft/FTOOLS (Blackburn 1995; Blackburn et al. 1999), ATNF pulsar catalog (Manchester et al. 2005), PRESTO (Ransom 2011), corner (Foreman-Mackey 2016), emcee (Foreman-Mackey et al. 2013), IDL.16 Veusz,17 Holoviews.18Attached Files
Published - Bachetti_2021_ApJ_908_184.pdf
Accepted Version - 2009.10347.pdf
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Additional details
- Eprint ID
- 107933
- Resolver ID
- CaltechAUTHORS:20210205-093236142
- Fulbright Foundation
- Science and Technology Facilities Council (STFC)
- Created
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2021-02-05Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, Space Radiation Laboratory, NuSTAR