Signals puzzling scientists for 17 years came from microwave oven

MELBOURNE: The source of mysterious signals that left astronomers at Australia's most famous radio telescope scratching their heads for 17 years has finally been found - and it's a microwave oven!

Scientists first detected the interference in 1998, which they assumed was from lightning strikes, but earlier this year they finally found the real culprit.

It turned out that a microwave oven in the kitchen at the Parkes observatory which was used by staff members to heat up their lunch was the source of the signals.

The signals "were reasonably local, say within 5km of the telescope," said Simon Johnston, head of astrophysics at the CSIRO, the national science agency.

Researchers assumed the signals - which appeared only once or twice a year - were coming from the atmosphere, possibly linked to lightning strikes.

In January this year they installed a new receiver which monitored interference, and detected strong signals at 2.4 Gigahertz (GHz), the signature of a microwave oven.

Immediate testing of the facility microwave oven did not show up with perytons. Until they opened the oven door before it had finished heating, Guardian reported.

"If you set it to heat and pull it open to have a look, it generates interference," Johnston said.

Astronomers generally operate the telescope remotely and do not reside at Parkes.

However, there were a number of operational staff members who maintained the facility and used the microwave oven to heat their coffee or lunch.

The "suspicious perytons" were only detected during the daytime and not during the evening when all the staff had finished their shift, Johnston said.