....Notes on Tau sky monitors....
    RAChamberlin, 22Nov99

The CSO is currently operating two tau sky monitors, both
of them provided by the NRAO.  One of them is a heterodyne, narrowband
monitor centered on 225GHz, and the other is a broadband instrument
with a filter limiting its response to the 350 micron window.
Both instruments use a "skydip" technique to determine
the atmospheric opacity.    

The 225GHz taumeter was installed at the CSO in 1989 and has
been operating continuously since then.  Versions of the same
instrument have been operated at other astronomical sites such as the
South Pole and the future MMA site in Chile.   

The 350 micron taumeter was constructed by Simon Radford of the
NRAO in Tucson, and installed at the CSO in 1998.   Indentical versions
of the same instrument are in operation at the South Pole,
and at the future MMA site in Chile.

For more information on taumeters or site survey results contact 
SRADFORD@NRAO.EDU, or  CHAM@POLIAHU.SUBMM.CALTECH.EDU.