A radio perspective on SA's 2009 solar eclipse

27 January 2009

The MeerKAT team in Cape Town joined the countrywide celebrations of a partial solar eclipse and the official launch of the International Year of Astronomy 2009 in South Africa, on Monday 26 January 2009.

Simon Ratcliffe reports that they measured microwave energy from the sun with the small PED telescope on the grounds of the South African Astronomical Observatory in Cape Town. The PED observation showed the microwave energy from the sun returns to normal (increases) as the eclipse passes from a maximum dimming of 54%. This is less than the optical obscuration of 65% at the site since the radio energy at the observing frequency of 1420 MHz is expected to come primarily from the sun's atmosphere.

They also hooked up with the MeerKAT prototype dish at the Hartebeesthoek Radio Astronomy Observatory near Krugersdorp for the same measurements. Some initial network challenges meant that they could only start measurements a while after the eclipse had already started, but found a similar increase in microwave energy as the shadow of the moon over the sun becomes smaller. The corresponding optical view of the sun at the beginning and end of the observation are superimposed on the graph.