Hirofumi Sugimoto and Hiroshi Ogawa
Abstract: The encounter of meteoroids released by comet 209P/LINEAR had been predicted on 25th May (λʘ = 63.8°). At λʘ = 63.708° (May 25, 05h30m UT), some possible of meteor activity has been detected by using radio meteor observations from around the world. A maximum ZHRr = 14 ± 2 was recorded. This activity level was about half of the level recorded during the previous outburst in 2014 (estimated ZHRr = 26).
An outburst of meteor activity related to comet 209P/LINEAR was observed in 2014. The estimated activity level by worldwide radio meteor observations was ZHRr = 26 at 62.91° (Sugimoto, 2014).
For 2022, an encounter with meteoroids released by comet 209P/LINEAR was expected on 25th May around 08h (λʘ = 63.8°) (Rendtel, 2021).
Radio meteor observations allow meteor activity to be monitored continuously even with bad weather or during daytime. Besides, the radiant elevation problem is solved by organizing this as a worldwide project. One of the worldwide projects is the International Project for Radio Meteor Observations (IPRMO). IPRMO uses the Activity Level index to analyze the meteor shower activity (Ogawa et al., 2001).
This research adopted the ZHRr index (Sugimoto, 2017). The ZHRr index is very useful and has been used in many past articles because it is helpful to compare radio observations to visual observations.
Figure 1 shows the result based on the calculation of the ZHRr using 35 datasets from around the world collected by the Radio Meteor Observation Bulletin (RMOB).
The peak occurred at λʘ = 63.708° (May 25, 5h30m UT). The zenithal hourly rate reached ZHRr = 14 ± 2. The distinct increase in activity started at λʘ = 63.428° (May 24, 22h30m UT), and ended at λʘ = 63.828° (May 25, 8h30m UT). Although the Activity Level Index which is adopted by IPRMO was only a reference value, a small peak has been detected at the same time (see Table 1).
Table 1 – The estimated ZHRr and Activity Level Index (AL), Activity Level Index is a reference values.
|Time (UT)||λʘ||ZHRr||Activity Level|
|May 24 23h30m||63˚.468||29||3±1||13||0.1±0.1|
|May 25 0h30m||63˚.508||25||4±1||12||0.2±0.2|
|May 25 1h30m||63˚.548||28||3±1||15||0.1±0.2|
|May 25 2h30m||63˚.588||26||4±1||12||0.0±0.1|
|May 25 3h30m||63˚.628||27||10±1||21||0.3±0.3|
|May 25 4h30m||63˚.668||22||10±1||8||0.2±0.1|
|May 25 5h30m||63˚.708||23||14±2||10||0.4±0.3|
|May 25 6h30m||63˚.748||21||11±2||10||0.1±0.2|
|May 25 7h30m||63˚.788||23||8±1||10||0.1±0.2|
|May 25 8h30m||63˚.828||24||4±1||14||0.2±0.1|
|May 25 9h30m||63˚.868||25||2±1||17||-0.0±0.2|
Figure 2 shows the estimated component by using the Lorentz profile (Jenniskens et al., 2000). It had a maximum ZHRr = 14 at λʘ = 63.708° (May 25, 5h30m UT) with Full width half maximum (FWHM) = -2.5 / +2.0 hours. The ascending branch was longer than the descending branch.
In 2014 (previous outburst), the component of the meteor activity was estimated as ZHRr = 26 with -3.0/ +3.0 hours at λʘ = 62.909° (May 24, 8h30m UT). The 2022 activity therefore was about half of the activity level of 2014 (see Table 2).
Table 2 – Estimated components of meteor activity in 2022 and 2014.
|ZHRr (2022)||May 25 5h30m UT||63˚.708||14||-2.5/+2.0|
|ZHRr (2014)||May 24 8h30m UT||62˚.909||26||-3.0/+3.0|
The observers who provided data were as following:
Chris Steyaert (Belgium), Felix Verbelen (Belgium), Johan Coussens (Belgium), HFN-R1 (Czech Republic), SVAKOV-R12 (Czech Republic), NACHODSKO-R5 (Czech Republic), DDMTREBIC-R3 (Czech Republic), Jean Marie F5CMQ (France), Balogh Laszlo (Hungary), Istvan Tepliczky (Hungary), Mario Bombardini (Italy), Hirofumi Sugimoto (Japan), Hironobu Shida (Japan), Hiroshi Ogawa (Japan), Kenji Fujito (Japan), Masaki Kano (Japan), Masaki Tsuboi (Japan), Minoru Harada (Japan), Nobuo Katsura (Japan), Norihiro Nakamura (Japan), Juan Zapata (Mexico), Rainer Ehlert (Mexico), Salvador Aguirre (Mexico), RAFAEL MARTINEZ (Puerto Rico),Karlovsky Hlohovec Observatory (Slovakia), Ian Evans (UK), Philip Norton (UK), Philip NortonVert (UK), Philip Rourke (UK), Eric Smestad_KC0RDD (USA), Richard Schreiber (USA), Stan Nelson (USA)
We wish to thank Pierre Terrier for developing and hosting rmob.org.
Jenniskens P., Crawford C., Butow S. J., Nugent D., Koop M., Holman D., Houston J., Jobse K., Kronk G., and Beatty K. (2000). “Lorentz shaped comet dust trail cross section from new hybrid visual and video meteor counting technique imprications for future Leonid storm encounters”. Earth, Moon and Planets, 82–83, 191–208.
Ogawa H., Toyomasu S., Ohnishi K., and Maegawa K. (2001). “The Global Monitor of Meteor Streams by Radio Meteor Observation all over the world”. In, Warmbein Barbara, editor, Proceeding of the Meteoroids 2001 Conference, 6-10 August 2001, Swedish Institute of Space Physics, Kiruna, Sweden. ESA Publications Division, European Space Agency, Noordwijk, The Netherlands, 189–191.
Rendtel J. (2021). “2022 Meteor Shower Calendar”. International Meteor Organization
Sugimoto H. (2014), “2014 May Camelopardalids (209P/LINEAR) Radio results” on the website, http://www5f.biglobe.ne.jp/~hro/Flash/2014/CAM/index.html
Sugimoto H. (2017). “The New Method of Estimating ZHR using Radio Meteor Observations”. eMetN, 2, 109–110.