Detectability of optical transients with timescales of sub-seconds

TL;DR

This study conducted a search for optical transient sources lasting 0.1 to 1.3 seconds using high-cadence, wide-field observations, resulting in upper limits on their occurrence rates around the ecliptic and Galactic plane.

Contribution

It introduces a robust detection method for sub-second optical transients using simultaneous observations from two independent systems and provides the first upper limits on their event rates.

Findings

No candidate events detected in the dataset.

Upper limits on event rates are approximately 0.090 and 0.38 hr^{-1} deg^{-2} for magnitudes 12 and 13.

The study discusses future prospects for sub-second transient surveys.

Abstract

We search for optical transient sources with durations of $\sim 0.1$ to $\sim 1.3$ s using a dataset obtained in the Organized Autotelescopes for Serendipitous Event Survey (OASES) observation campaign. Since the OASES observations were carried out using two independent wide-field and high-cadence observation systems monitored the same field simultaneously, the obtained dataset provides a unique opportunity to develop a robust detection method for sub-second optical transients. In the dataset of a selected field around the ecliptic and the Galactic plane, we find no astronomical event candidate that satisfies our detection criteria. From the non-detection result, we derive an upper limit on the event rate of sub-second transients around the ecliptic and the Galactic plane for the first time, obtaining $\sim 0.090$ and $\sim 0.38~{\rm hr^{-1}~deg^{-2}}$ for $m = 12$ and 13 Vmag, respectively. In addition, future prospects of the sub-second scale transient event surveys are discussed.