1Giga-bps記録によるVERA内部測地VLBI観測の初期3年間の成果

抄録

Geodetic VLBI observations bounded within the VERA network started in November 2004 in order to monitor positions of the VERA radio telescopes with 10^-9 accuracy. The VERA geodetic VLBI observations are the first series of regular observations that use a 1Gbps recording system. Increasing of recording rate to 1Gbps improves fringe detection sensitivity and reduces the scan length needed for fringe detection. Using a new scheduling algorithm that takes advantage of this increase in sensitivity, the number of scans in one 24-hour session has increased from 2 to 3 times that of geodetic VLBI with the conventional bandwidth. Forty eight observing sessions were operated during the first 3 years since 2004. Coordinates of the VERA antenna reference points and baseline lengths are estimated with errors of a few mm. The increase in the number of scans thus led effectively to reduce the scatter of the results by 1.4 times among the observing sessions, as well as to reduce standard deviations of estimated coordinates of antennas by 1.5 times in individual sessions. Secular variations are detected from the time series of observed baseline lengths.