H2O Maser Emission in the Starburst Galaxy NGC 253

We report Very Large Array CnB- and A-configuration observations of the 22 GHz H2O maser line toward the starburst galaxy NGC 253. We detect a broad, highly blueshifted (VLSR = 120.5 km s-1) H2O line coincident with the continuum source TH4, which is believed to be a supernova remnant. The H2O maser emission arises from an area whose size is smaller than 0.9 pc. A weaker feature at VLSR = 60.0 km s-1 is also seen at the same position. We also detect the extended 1.3 cm continuum along the galactic disk of NGC 253, as well as the two central continuum sources TH2 and TH4.