Description
Repeating fast radio bursts (FRBs) are prime targets for high–time-resolution optical searches
aimed at identifying fast optical counterparts. Between October 2022 and December 2023, we
monitored the highly active repeater FRB 20220912A at the Asiago Observatory using the fast
photon-counting instruments Aqueye+ and IFI+Iqueye. During prolonged optical observations,
we identified short (∼1 ms) statistically significant optical pulses, here referred to as fast optical
bursts (FOBs).
To assess the nature of these events, we performed a detailed foreground characterization using
archival Aqueye+ observations of a comparison field, centered on the faint millisecond pulsar
PSR J1023+0038. Exploiting the availability of both on-source and on-sky detectors, we find that
about 60% of significant events are detected simultaneously in both regions, consistent with diffuse
atmospheric contamination, likely associated with meteor activity. A comparable fraction is observed
in the FRB 20220912A field, suggesting that the detected FOBs are dominated by foreground
events. Further optical monitoring and coordinated multi-wavelength campaigns, including Iqueye
at Gemini South, are required to improve the statistics and to search for any excess of isolated
on-source events potentially attributable to the FRB.