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A lawnmower has been blamed for wrongly
triggering sensors that predict when the Northern Lights will be visible in
the UK.
A
red alert issued via the Aurora
Watch mailing list was withdrawn after sensor readings were found to
be "spurious".
An
investigation revealed a lawnmower had got too close to one sensor, triggering
a "massive spike" in data.
Aurora
Watch said it was looking into ways to avoid the incident being repeated.
The
bogus alert was issued during the afternoon of 23 August, after a magnetometer
at the University of Lancaster recorded a surge in geomagnetic activity.
Trim grass
Aurora
Watch is run by scientists at the university and takes readings from lots of
magnetometers to work out when the aurora borealis will be visible across
Britain.
The
project draws on magnetometers in Lancaster, Aberdeen, the Faroe Islands and
further field.
The
alert was withdrawn four hours after being released as it emerged only
one sensor had recorded the spike in activity.
A
later update posted to the Aurora Watch webpage said an investigation had
revealed that a groundskeeper using a "sit-on mower" to trim grass had been
driving too close to the sensor, prompting the spike.
"We'll
work with the facilities team to try and avoid an incident such as this
occurring in the future," said the scientists.
They
explained any metal placed on the instrument or machinery operating nearby
could trick it into recording more activity than was actually present.
Readings
from the Lancaster sensor were not typically used to trigger alerts, they
said, but problems with the main sensor in Aberdeen on 23 August meant it had
become the lead monitor.
