Positions of the SiO masers in Orion-KL : anisotropy on a scale of 70AU.

Interferometric measurements of the SiO masers in Orion are reported. The observations were obtained using a 64 channel set of 250 kHz filters, and data taken from Orion were interspersed with observations of reference quasars. The relative maser phases were determined to be within 0.01 arcsec of 0.10 arcsec for a 15 km/sec maser and within 0.02 arcsec of -0.10 arcsec for the 16 km/sec maser feature, with a constant -0.06 radian offset at all baselines. The two masers are separated along a NW-SE axis and display a velocity shift opposite that expected of a high-velocity gas and similar to that present in maps of a 2(2)-1(1) SO line. The masers are aligned with two lobes of high-velocity gas and are asymmetric, indicating that IRc2 is the source of molecular outflow in Orion.