2010ApJ...712L...5R

We report on the detection of strong circularly polarized emission from the transient bursting source GCRT J1745-3009 based on new analysis of 325 MHz Giant Metrewave Radio Telescope observations conducted on 2003 September 28. We place 8 R_☉ as the upper limit on the size of the emission region. The implied high brightness temperature required for an object beyond 1 pc and the high fraction of circular polarization firmly establish the emission as coherent. Electron cyclotron or plasma emission from a highly subsolar magnetically dominated dwarf located ≤4 kpc away could have given rise to the GCRT radio emission.