Next: Linear Regression of the
Up: Special Calibration Tools and
Previous: Antenna Gains
Simultaneous observations with dual receivers (230/690 GHz) are supported
at the SMA. This is a nice feature for observations at high frequency.
At high frequencies of submillimeter wavelengths, strong calibrators
become rare. The phase variation due to changes of water vapor in the
atmosphere might be monitored by the observation of a calibrator at lower
frequency (230 GHz). The 690 GHz phase appears to be linearly correlated
with the phase at 230 GHz under normal circumstances.
The phase variation monitored at 230 GHz
might be transferred to 690 GHz. The transferred phase variation
might be used to correct for phase variation in the observation at 690 GHz.
This technique requires a good stability of the instruments at both 230
and 690 GHz. Based on the experiments in the spring 2005, a procedure
for the phase transfer between 230 and 690 GHz is provided below
for the off-line calibration concerns:
Jun-Hui Zhao (miriad for SMA)