Modeling the Solar Limb Brightening at 21 cm Wavelength Using Observations With an Interferometer of 3 Small Radio Telescopes.

We present modeled images of the Sun from measurements of the interferometric amplitude and closure phase from a 3-baseline interferometer operating at 21 cm wavelength. The data were obtained from 9 June through 7 August 2006. During this period the solar activity was relatively quiet and the data is well fit using a model with equatorial limb brightening which contributes 30 +/- 10 percent of the total solar radio flux density. Modeling the image with circularly symmetric brightening or polar limb brightening does not fit the measurements providing clear evidence that the limb brightening is largely equatorial. During the period of the observations the days with asymmetric images, as indicated by values of the closure phase which deviate from zero or 180 degrees, are well fit by adding from a single sunspot whose best fit position is consistent with the position of the major sunspot in the optical image for that day.