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Simultaneous optical and radio observations of Perseids

From today (August 11th) up until Friday the yearly Perseids meteor shower will have its peak. This phenomenon is not only interesting for amateur astronomers, professional astronomers will be observing them as well.

Published by the editorial team, 11 August 2020

This year, scientists will be observing the meteor swarm with both AARTFAAC (Amsterdam-ASTRON Radio Transients Facility And Analysis Center) and optical cameras simultaneously, with the goal to achieve new scientific insights into meteors. The ionised trails left by meteors when they burn up in the atmosphere can reflect radio waves from, for example, radio and TV stations, and radio amateurs use this reflection to count meteors, both at night and during the day.

AARTFAAC is a LOFAR based system capable of generating real time images of the entire sky, on radio frequencies between 10 and 80 MHz. Simultaneously with the AARTFAAC observations, the Meteor Section of the Royal Netherlands Association for Meteorology and Astronomy (KNVWS) will use a network of cameras to observe the Perseids. Felix Bettonvil, of the Meteor Section: “The optical observations enable us to triangulate the positions of the meteors. And by performing optical observations we can also be certain that AARTFAAC is registering the radio signal of the meteors and not, for example, that of a passing airplane.” Generally, the ASTRON radio telescope LOFAR studies radio waves from the far Universe, studying its origin, but it is also very capable of looking much closer to home.

Location of the optical cameras participating in the project. (copyright: openstreetmap contributors/CartoDB)

Both professional astronomers such as Cees Bassa (ASTRON) and Mark Kuiack (University of Amsterdam) and amateur astronomers are involved in this project, building a bridge between optical and radio astronomy.

In 2015 astronomers, using the American radio telescope LWA (Long Wavelength Array), noticed that these meteors possibly also emit radio waves themselves when coming into contact with the Earth’s atmosphere. “Or rather, the meteors ionise the air surrounding them, and that ionised air reflects, and apparently also sends out, radio waves,” explains Tammo Jan Dijkema, scientific software engineer at ASTRON and amateur radio astronomer.

Most suitable instrument

The researchers hope to reproduce the results of the LWA telescope. “AARTFAAC is by far the best telescope to do this,” Dijkema says. “No other radio instrument can map the entire sky in such detail.” The scientists also want to refine the method of observing meteors with both radio telescopes and optical cameras simultaneously. Dijkema: “This time we will be looking at the Perseids, but there are always meteors to observe.” Apart from that, the researchers also hope to find out why the Perseids are sending out radio waves, which possibly can teach them more about the nature of meteors.

While a radio telescope is not hindered by clouds and can even track meteors during daytime, optical cameras cannot. Therefore, a clear night is needed for these observations. Dijkema: “Currently the night from Wednesday to Thursday, from August 12th to 13th, seems the most suitable night for our observations, but the night before will also show many Perseids.”

Amateur radio astronomers of the Dwingeloo Radio Telescope (CAMRAS) will also look at the Perseids with radio. They will give an online talk about this on Wednesday, at 8 PM.



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