CubeSats Reach the Millisecond X-Ray Domain: Crab Pulsar Timing with SpIRIT/HERMES

TL;DR

This paper demonstrates that the compact HERMES instrument on the SpIRIT CubeSat can achieve millisecond timing accuracy in X-ray observations, enabling detailed pulsar studies and potential gamma-ray burst monitoring.

Contribution

First demonstration of millisecond-scale X-ray timing with a CubeSat instrument, showing its capability for high-energy astrophysics in a compact form factor.

Findings

Detected the Crab pulsar's double-peaked pulse profile with 5σ significance.

Collected approximately 57,000 photons in 730 seconds in the 3 keV–2 MeV range.

Achieved millisecond timing accuracy, previously only possible with flagship observatories.

Abstract

The High Energy Rapid Modular Ensemble of Satellites (HERMES) instrument is a compact X/$\gamma$-ray spectrometer operating on board the 6U (11 kg) SpIRIT CubeSat. The payload is particularly well suited for the observation of cosmic transients such as Gamma-Ray Bursts and bright pulsars thanks to its unique broadband sensitivity from a few keV to a few MeV and the temporal resolution down to half a microsecond. We report here the detection of the $\sim$33~ms Crab pulsar double-peaked pulse profile obtained by considering the canonical Crab ephemerides as provided by the Jodrell Bank catalog. We collected approximately 5.7$\cdot$10$^4$ photons from 730~s of observations, in the 3 keV -- 2 MeV energy band, during a single operation, and achieved a 5$\sigma$ pulse profile significance in the 3--11.5 keV energy band with binning at the ms scale. The results demonstrate that SpIRIT/HERMES can achieve millisecond timing accuracy at high energies and, thanks to its wide field of view and broad energy band, has the potential to contribute to GRB monitoring in the near future. Such capabilities were previously the domain of flagship observatories, underscoring the performance of the HERMES instrument with its compact form factor.