Deriving a VGOS-Band Flux Density Catalog from Real Geodetic VLBI Observations

Efficient scheduling in the VLBI Global Observing System (VGOS) requires accurate knowledge of source flux densities at 3–11 GHz. However, the lack of such data leads to fixed 30-second scan durations, often resulting in sub-optimal use of observing time and limited scan counts per session. To address this, we present a method to estimate flux density per projected baseline length bin (in 1000 Km interval) using real VGOS observations, accounting for intrinsic source structure while minimizing system noise effects. From these baseline bin flux estimates, we compute the integration time needed to achieve a target signal-to-noise ratio (SNR) of 15 per bin. A dedicated pipeline has been developed to dynamically determine observation duration using either individual SEFDs, enabling flexible and accurate flux-based scheduling. Comparative analysis with SKED’s power-law flux model reveals its limitations in capturing detailed source structure, especially at higher frequencies. Applied to one of 19 VGOS sessions, our approach increased the total number of observations by 24%, highlighting its potential to enhance scan efficiency, improve geodetic precision, and support better classification of compact versus extended sources