A Message from the SPARO P.I., Dr. Giles Novak

Dear collaborators and friends:

First light observations with SPARO, CARA's submillimeter polarimeter, took place at the Caltech Submillimeter Observatory, during May 3rd-6th. The weather was reasonably bad, but the instrument performed very well: Configured with an 800 micron bandpass for CSO observations, SPARO demonstrated low instrumental polarization ( < 0.5% ), high polarimetric efficiency ( > 90% ), good spectral filtering, 3-day He-4 hold-time, reasonable NEFD given the weather conditions and the lack of AR coating on the optics (15 Jy for a tau-230 of about 0.14), and just two dead pixels.

We were able to achieve statistical polarization errors near 0.2% on Sagittarius B2(North), our main science target. This is potentially a new science result - we won't know until we finish analyzing our polarimetric calibrations and checks for systematic errors. As we prepare the instrument for the 1999 Winter-over on the Viper telescope, our biggest remaining problem is that the dewar has more microphonics than we think we can tolerate for the South Pole observations.

cheers,

Giles, for the Submillimeter Polarimeter for Antarctic Remote Observations (SPARO) project.