Session 42 - Molecular Clouds: Models and Observations.
Display session, Tuesday, June 11
Great Hall,

## [42.10] Water Masers in Orion

R. A. Gaume (USNO), T. L. Wilson (MPIfR), F. J. Vrba (USNO), K. J. Johnston (USNO), J. Schmid-Burgk (MPIfR)

The VLA of the NRAO and the IRCAM of the USNO were used to image the H_2O masers at a wavelength of 1.3 cm and the infrared emission at the IR J, H, and K bands in the Orion region of star formation. The IR and radio frames have been aligned to an accuracy of \pm 0.1'', and overlays of the H_2O maser and IR emission are presented. A new region of H_2O maser emission was detected nearly 2' south of IRc2, near the OMCS outflow region. The strongest H_2O masers in OMCS are distributed along a SE/NW 0.5'' line. A velocity gradient of 65 km s^-1 is found along this line. This site is identified as the most likely position of the source driving the OMCS molecular outflow. OMCS H_2O masers are found in proximity to several very reddened IR point sources.

The spatial distribution of the H_2O masers toward Orion BN/KL generally agrees with previous VLBI observations. The shell'' H_2O masers, found toward IRc2, are distributed along a 1.5'' line. The shell'' masers toward IRc2 cover a velocity range of 26 km s^-1. Although more complex than the masers toward OMCS, the velocity distribution of the IRc2 shell'' masers is discussed.