We report the first detection of radio emission from any anomalous X-ray pulsar ( AXP ) .
Data from the Very Large Array ( VLA ) MAGPIS survey with angular resolution 6 ^ { \prime \prime } reveals a point-source of flux density 4.5 \pm 0.5 mJy at 1.4 GHz at the precise location of the 5.54 s pulsar XTE J1810 - 197 .
This is greater than upper limits from all other AXPs and from quiescent states of soft gamma-ray repeaters ( SGRs ) .
The detection was made in 2004 January , 1 year after the discovery of XTE J1810 - 197 during its only known outburst .
Additional VLA observations both before and after the outburst yield only upper limits that are comparable to or larger than the single detection , neither supporting nor ruling out a decaying radio afterglow related to the X-ray turn-on .
Another hypothesis is that , unlike the other AXPs and SGRs , XTE J1810 - 197 may power a radio synchrotron nebula by the interaction of its particle wind with a moderately dense environment that was not evacuated by previous activity from this least luminous , in X-rays , of the known magnetars .