100-MU-M ARRAY POLARIMETRY FROM THE KUIPER-AIRBORNE-OBSERVATORY - INSTRUMENTATION, TECHNIQUES, AND 1ST RESULTS

The University of Chicago far-infrared array polarimeter, STOKES, is the first multiple-beam polarimeter for far-infrared astronomy. Observations are made from the NASA Kuiper Airborne Observatory. Two orthogonal components of linear polarization are detected simultaneously by corresponding pairs of bolometers in two 32-detector arrays. Removal of the effects induced by the polarimeter and telescope from the measured signals is complicated by the multiple optic axes defined by the 32 independent pixels of the instrument. Novel observing and data-analysis techniques are used to overcome the inherent difficulties of array polarimetry. Results from the first observing flights with the new instrument are reported for the molecular clouds W3 and W51. The measurements show that the magnetic-field structure in both clouds is nonuniform on the scale of 0.5-1.5 pc. This is consistent with molecular line and Zeeman observations that indicate the presence of turbulent velocities and significant small-scale structure. Preliminary results from the second flight series have yielded approximately 40 new measurements in the Sgr A complex. These results indicate that modifications made since the first flights have significantly improved the performance of STOKES.