Traditional optical astronomy is limited to sub-second timescales due to the readout speed of detectors and readout noise limitations to sensitivity in short exposures [1]. Our Ultra-Fast Astronomy (UFA) program aims to survey the optical night sky at such rarely explored timescales via developing Ultra-Fast photon detectors [2].

There exist many interesting known or proposed astrophysical events in the sub-second domain. Some of them are transient events, which are energetic events in the universe that commonly originate from compact objects and their related extreme environments [3]. Some celestial objects may also exhibit ultra-fast variability due to their emission nature. With Ultra-Fast photon detectors, we may also investigate the quantum optics effects on celestial objects or en...[ Read more ]

Traditional optical astronomy is limited to sub-second timescales due to the readout speed of detectors and readout noise limitations to sensitivity in short exposures [1]. Our Ultra-Fast Astronomy (UFA) program aims to survey the optical night sky at such rarely explored timescales via developing Ultra-Fast photon detectors [2].

There exist many interesting known or proposed astrophysical events in the sub-second domain. Some of them are transient events, which are energetic events in the universe that commonly originate from compact objects and their related extreme environments [3]. Some celestial objects may also exhibit ultra-fast variability due to their emission nature. With Ultra-Fast photon detectors, we may also investigate the quantum optics effects on celestial objects or enhance existing astronomical observations via improved temporal resolution.

In this research, we have developed the Single-Photon Imager for Nanosecond Astrophysics (SPINA) system, which utilizes a position-sensitive silicon photomultiplier (PS-SiPM) detector for single-photon imaging. We designed and constructed the readout electronics, data preprocessing algorithms, readout software, and mechanical structure for the SPINA system and readied it for on-sky testing. The initial on-sky testing took place in July 2022, and despite unfavourable weather conditions, we captured photons from multiple stars to calibrate our SPINA system. During on-sky testing, we successfully observed the atmospheric scintillation effect on stellar profiles and photon flux at millisecond and microsecond timescales, demonstrating the SPINA system’s capability for ultra-fast astronomical observations. Additionally, we propose enhancements and future experiments with the SPINA system and its successors.