Electronic Telegram No. 5055 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network ARID METEORS 2021 P. Jenniskens, SETI Institute and NASA Ames Research Center; S. Heathcote, Cerro Tololo International Observatory, AURA; E. Jehin, University of Liege; M. Towner, Curtin University; T. Hanke, H.E.S.S. Collaboration; W. Cooney, Houston Astronomical Society; and D. Lauretta, University of Arizona, report that CAMS video-based meteoroid-orbit survey networks detected the predicted Arid meteor-shower outburst caused by the earth encountering the debris ejected by comet 15P/Finlay during its activity outbursts in 2014 and 2015 (cf. CBET 5049). Under partially clear skies, nineteen Arid meteors were detected by CAMS Chile (with networks operated by J. Rojas, J. Vilaza, and T. Abbott), six by CAMS Namibia, six by CAMS Texas, and two by CAMS Australia during 2021 Oct. 6d11h04m-7d04h10m UTC (cf. website URL http://cams.seti.org/FDL/ for 2021 Oct. 7), corresponding to the solar- longitude range 193.12-193.83 deg (equinox J2000.0). Centered on solar longitude 193.68 +/- 0.17 deg (Oct. 7d00h41m UTC), these meteors radiated from a median geocentric radiant at R.A. = 256.8 +/- 0.8 deg, Decl. = -48.3 +/- 0.6 deg (equinox J2000.0) with geocentric velocity 10.5 +/- 0.3 km/s, slightly northwest from the 1995 dust-ejecta radiant (cf. CBET 5046), but still in the constellation of Ara. Most of the Arid meteors were faint, with a steep magnitude-distribution index of 4.2 +/- 0.6. Median orbital elements are as follows: a = 3.36 AU, q = 0.991 +/- 0.002 AU, e = 0.705 +/- 0.120, i = 6.7 +/- 1.3 deg, Peri. = 348.3 +/- 1.8 deg, Node = 13.69 +/- 0.17 deg (equinox J2000.0). The predicted radiant was at R.A. = 256 deg, Decl. = -48 deg, with geocentric velocity 10.7 km/s (cf. CBET 5049), in good agreement. Visual observer T. Cooper (Astronomical Society of Southern Africa) described two Arid meteors of magnitude +1 and +2 as "both very slow, noticeably orange, and [of] sparkling appearance". Jenniskens adds that the outburst was also detected by radio forward- meteor-scatter observations, summarized by H. Sugimoto and H. Ogawa of the International Project for Radio Meteor Observations. Results show enhanced rates from solar longitude 193.50 to 193.75 deg, peaking at 193.7 deg, corresponding to Oct. 7d01h UTC (cf. https://iprmo.org/flash/arids-2021.html). Their preliminary Zenith Hourly Rate is about 80 Arid meteors/hr, higher than that from the 1995 dust-trail encounter. J. S. Bruzzone, Astronomy Department, Faculty of Sciences, UdelaR, Igual, Montevideo; D. Janches, ITM Physics Laboratory, Goddard Space Flight Center, NASA; R. Weryk, Department of Physics and Astronomy, University of Western Ontario; and J. L. Hormaechea, Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de, La Plata, and Estacion Astronomica Rio Grande, report a strong detection of the Arid meteor-shower outburst associated with comet 15P using the Southern Argentina MEteor Radar Orbital System (SAAMER-OS) centered at Oct. 7 at 1h UT and lasting over 7 hours. The detection matches the predicted time of the peak by Ye and Vaubaillon (cf. CBET 5049). The outburst was centered at R.A. = 255.01 deg, Decl. = -48.47 deg (equinox J2000.0) with meteor velocities of 10.9 km/s based on wavelet analysis using 690 meteors and in close agreement with predictions. The detection is 11.7 times above the annual average for that location. Average computed orbital elements are as follows: a = 3.634 AU, e = 0.7276, i = 7.0747 deg, Peri. = 347.673 deg, Node = 14.171 deg (equinox J2000.0), q = 0.98974 AU. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 October 9 (CBET 5055) Daniel W. E. Green