Observational results of the 2022 τ-Herculid outburst from California and Hawai’i

Abstract This study presents observational results of the 2022 outburst of the $\tau$-Herculid meteor shower. The event is attributed to a dust trail released during the 1995 fragmentation of its parent body, comet 73P/Schwassmann–Wachmann 3. Observations were carried out at the Goat Mountain Astronomical Research Station (GMARS) in California, where favorable conditions coincided with the predicted peak time. The outburst was also captured by a live camera located at the Subaru Telescope site on Maunakea, Hawai’i.At GMARS, video observations detected a peak at 04:46 UT on May 31, with the (Z) hourly rate (i.e., the hourly rate corrected for radiant altitude by applying a zenith attraction correction) reaching $173 \pm 26$. The corresponding flux was estimated to be $(6.1 \pm 0.95) \times 10^{-3}$ km$^{-2}$ s$^{-1}$. A gradual decline in activity was recorded at Maunakea after the peak, confirming the absence of any major secondary maxima. The observed timing and temporal profile of the activity agree well with predictions based on dust trail modeling, suggesting the detection of relatively large meteoroids ejected at a large negative velocity of approximately -27 m s$^{-1}$. Additionally, weak activity observed at Maunakea on the nights before and after the main peak implies the presence of more broadly dispersed dust trails originating from older ejection epochs. These findings support the conclusion that the 1995 outburst of the parent comet was a large-scale event that significantly contributed to the observed meteor activity.