>Date: Fri, 15 May 98 18:44:41 CDT
>From: novak@clark.phys.nwu.edu (Giles Novak)
>Subject: SPARO first light
>
>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.
>
>We'll be posting details on the SPARO home page
>(http://belmont.astro.nwu.edu/).
>
>cheers,
>
>Giles, for the Submillimeter Polarimeter for Antarctic Remote Observations
>(SPARO) project.