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Apertif sees Perytons in real time

Submitter: Vanessa Moss
Description: We are currently carrying out a month of Apertif Science Verification Campaign (SVC), with a focus on assessing the data quality of science data obtained by the time-domain and imaging teams. The week of 18th-25th March was the first time-domain week, where over 100 observations were carried out with a 93% success rate. These run on ARTS, the Apertif Radio Transient System, a beamformer plus GPU transient-search cluster built for real-time detections. On Wednesday 20th March, during the weekly Astronomy Group coffee in the echoing hallways of wing 1980, some of us were talking about the SVC over yellow cake, when Vlad Kondratiev suggested: why don’t you make some perytons? Excellent idea!

Perytons are a type of radio transient first discovered at the Parkes Radio Telescope in Australia, and later characterised by Emily Petroff (see the paper for details). They are generated when hungry, impatient humans rip open the doors of microwave ovens while they are still on (no joke). They have emission signatures highly similar to the astronomical fast radio bursts (FRBs) which the ARTS team is scientifically interested in. Perytons have high dispersion measures, which is quite unique for terrestrial RFI. You can distinguish real FRBs from perytons though, because perytons appear in all beams on the sky, not just a particular sky position. So this was deemed a good test of the real-time transient detection pipeline AMBER. A group of us were thus asked by the ARTS team to carry out a peryton detection experiment at Westerbork, since we would be on site for a tour already.

Joeri van Leeuwen sourced a microwave from the ASTRON guest house (thanks Ina), and Alexander Kutkin provided an extra microwave, so we took the two microwaves along with us to WSRT. Emily provided detailed setup plans (top left). In total we tried to emit 8 perytons, 4 each from the two microwaves (left middle, bottom). Half of these were generated inside the control building which does have some RFI shielding, and the other half were generated near the old cabinet building for RT6. We were not necessarily expecting success because only specific kinds of microwaves are capable of generating perytons due to safety measures, but amazingly we did generate one really bright one which was picked up clearly by the ARTS pipeline, in all 40 beams (right sub panel). We could also tell which microwave this was by matching the timestamps from our recorded data. This was a great way to verify the real-time capabilities of the ARTS transient detection, and an interesting experiment to carry out. Thanks to everyone involved in helping to make this possible: Joeri van Leeuwen, Leon Oostrum, Jan Pieter de Reijer, Emma Tiggelaar, Matthijs van der Wiel, Helga Denes, Sarrvesh Sridhar, Joe Callingham, Emily Petroff, and the WSRT operations team. Looking forward to seeing some analysis of these results in Leon’s upcoming PhD thesis!
Copyright: J. van Leeuwen / V. Moss
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