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The Submillimeter Polarimeter for Antarctic Remote Observations (SPARO) employs two nine-element arrays of 3He-cooled bolometers to measure linear polarization at ? = 450 ?m. It is operated at the focal plane of the Viper telescope, located at the Amundsen-Scott South Pole Station. SPARO obtains better sensitivity to degree-scale polarized submillimeter emission than can be currently achieved with any other experiment. We describe the design of SPARO's optics, detectors, and electronics. We also review the design of the SPARO cryostat, which has already been discussed in a previous paper. We discuss the performance of SPARO and Viper during observations at the South Pole in 2000, and we present polarimetric observations of NGC 6334 made with SPARO. Finally, we compare these observations with submillimeter polarimetric observations of the same source made at the Caltech Submillimeter Observatory and the James Clerk Maxwell Telescope, and we discuss the implications of these three data sets for the magnetic field in NGC 6334.

We present new submillimeter polarimetric observations of the Galactic center region, made using the SPARO polarimeter that operates at the South Pole. Compared with previous submillimeter polarimetry of this region, our measurements cover much more sky area, and they imply that the molecular gas in the central few hundred pc is threaded by a large scale toroidal magnetic field. We consider this result together with radio observations that show evidence for poloidal fields in the Galactic center, and with Faraday rotation observations. We compare all of these observations with a magnetodynamic model for the Galactic center.

We present an introduction to observing procedures and principles of analysis used in far-infrared polarimetry. The observing procedures are those for single-dish observations of thermal emission from aligned dust grains. We discuss techniques for removing backgrounds and for reducing and evaluating errors. The principles of analysis are those required for interpreting polarization maps and polarization spectra in terms of opacity, field structure, and variations in temperature and polarizing efficiency.