AAS 207th Meeting, 8-12 January 2006
Session 25 VO and Source Surveys
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[25.06] Monitoring Callibrators at Submillimeter Wavelengths

M.R. Darrah (University of Hawaii Hilo), S.R. Hostler, A.B. Peck, M.A. Gurwell (SAO-SubMillimeter Array)

One of the biggest challenges facing submillimeter wavelength interferometry is correcting for short timescale atmospheric phase fluctuations during the observations. Quasars sufficiently bright to use as calibrators are scarce, particularly at frequencies higher than 300 GHz. We present results of an ongoing monitoring program to determine the fluxes and variability of quasars at 230 and 345 GHz. The data is being collected at the Submillimeter Array (SMA) on Mauna Kea and reduced using MIR data reduction software. Quasars that have quality data spanning a time period of at least six months are included. The quasars have been sorted for those with a minimal variability in flux, making them reliable calibrators, and those whose variability make the fluxes unpredictable on a month to month basis. If the variability is below 30%, the quasar is considered stable enough to be a good candidate for calibration. If the variability exceeds this, while scientifically interesting, they are considered unreliable for planning future observations. Current and future telescopes will be able to make use of this list at 200-400 GHz. In addition, software is being developed at the SMA to transfer the phase solutions derived at these frequencies up to 690 GHz, where most quasars are nearly undetectable. This will allow us to correct the phase in the high frequency observations when both 230 and 690 GHz receivers are used simultaneously.

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