SPARO at South Pole
SPARO and the first team from Northwestern arrived at Pole on December
10th. Liquid Helium arrived at Pole on January 10. SPARO was operated on
Viper during Jan. 20th - Jan. 26th. We carried out a host of tests and
measurements, incuding instrument noise, synchronous offsets, software
interface, and pointing/focus.
The weather conditions during these six days were quite bad: a four-day
blizzard followed by two days of exceptionally high submillimeter opacity.
So we carried out the pointing and focus tests using a liquid-nitrogen
cooled "compact source" placed on the roof of a building located 1000 feet
from the telescope. Everything checked out nicely.
After removing SPARO, the upgraded Corona instrument was successfully
tested on Viper during the last three weeks of the season. Meanwhile,
warmed SPARO so that Greg and John could subsequently cool it down by
themselves as practice. The cooldown went well, and the winter-overs
now also done three Helium-3 cycles and numerous He-4 fills on their
We decided on a conservative schedule for the winter: start with the
instrument (Corona) and install the new one (SPARO) only after a few
of successful operation of Corona. In order to conserve liqiuid Helium,
SPARO was warmed up in mid-February. If all goes well, we'll begin
the first large-scale map of the magnetic field in our Galaxy's nucleus