Tau Herculids 2022: Rate, number density, population index and geometrical effects from visual data

We analysed visual observation data of the Tau Herculids collected between 2022 May 28 and June 1. The population index r is 2.4 for entire sample. For the pre-peak period we find r = 2 . 57 ± 0 . 23, the peak period yields r = 2 . 38 ± 0 . 06. The ZHR maximum of the 1995 ejecta from comet 73P/Schwassmann-Wachnann3 (SW3) is found at λ ⊙ = 69 . ◦ 450, i.e. May 31, 05 h 04 m UT ( ± 5 min) with a ZHR = 55 ± 7, corresponding with a spatial number density ND ≈ 380 × 10 − 9 km − 3 for meteoroids larger than 10 mg. An earlier maximum occurred at λ ⊙ = 69 . ◦ 207, i.e. May 30, centred at 23 h UT with a ZHR = 18 ± 3 and is tentatively associated with SW3-ejecta from 1892. Effects of the radiant shift due to the large zenith attraction of about 10 ◦ for the radiant close to the horizon are discussed. is one − 6 TAH meteor which was seen by two observers at the same site. Two session reports summarised the magnitude data over 2.5 and 3.0 hours, respectively, and are not considered in the separate pre-/ post-peak distributions.