Single-photon gig in Betelgeuse's occultation

TL;DR

This paper demonstrates the successful application of advanced SPAD array technology for high-resolution, precise measurements during Betelgeuse's occultation, revealing detailed stellar and observational insights.

Contribution

It introduces a novel use of SPAD arrays in astronomy, addressing data challenges with a generalized negative binomial model, and achieves high-precision measurements of Betelgeuse's diameter.

Findings

Achieved 1 microsecond temporal resolution in light curves.

Estimated optical cross-talk at 1.07%, confirming low noise impact.

Measured Betelgeuse's angular diameter as 57.26 mas.

Abstract

We present results from the occultation of Betelgeuse by asteroid (319) Leona on December 12, 2023, observed using a 64x64 pixel Single-Photon Avalanche Diode (SPAD) array mounted on a 10-inch telescope at the AstroCamp Observatory in Nerpio, Southeast of Spain, just a few kilometers from the center of the occultation shadow path. This study highlights remarkable advancements in applying SPAD technology in astronomy. The SPAD array's asynchronous readout capacity and photon-counting timestamp mode enabled a temporal resolution of 1 microsecond in our light curve observations of Betelgeuse. Our data analysis addressed challenges inherent to SPAD arrays, such as optical cross-talk and afterpulses, which typically cause the photon statistics to deviate from a Poisson distribution. By adopting a generalized negative binomial distribution for photon statistics, we accurately describe the observational data. This method yielded an optical cross-talk estimation of 1.07% in our SPAD array and confirmed a negligible impact of spurious detected events due to afterpulses. The meticulous statistical examination of photon data underscores our SPAD-array's exceptional performance in conducting precise astronomical observations. The observations revealed a major decrease in Betelgeuse's intensity by 77.78% at the occultation's peak, allowing us to measure Betelgeuse's angular diameter at 57.26 mas in the SDSS g-band. This measurement, employing a simplified occultation model and considering the known properties of Leona, demonstrates the potential of SPAD technology for astronomy and sets a new standard for observing ultra-rapid transient celestial events, providing a valuable public dataset for the astronomical community.