The coordinates of radio telescopes, which are part of the emerging VLBI Global Observing System, were estimated in a least squares unconstrained adjustment. The higher number of observations per time with better sky coverage, which these telescopes can produce, was optimally utilized by testing different intervals for the tropospheric delay estimation. We found that a short estimation interval of 15 min for the tropospheric gradients with a 45 min interval for the zenith wet delay perform best.