  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.
