Observing APOD with the AuScope VLBI Array.

Area of Science:

• Geodesy
• Astrophysics
• Satellite Technology

Background:

• Geodetic Very Long Baseline Interferometry (VLBI) community interest in observing satellites for co-location.
• The APOD-A nano satellite integrates Satellite Laser Ranging (SLR), Global Navigation Satellite Systems (GNSS), and VLBI in Low Earth Orbit (LEO).
• Limited prior VLBI observations of APOD-A hindered frame tie studies due to non-standard procedures.

Purpose of the Study:

• To present the first comprehensive attempt at observing the APOD-A satellite using a VLBI network over multiple passes.
• To establish and validate a process chain for non-standard satellite VLBI observations.
• To prepare the global VLBI network for future co-location satellite missions.

Main Methods:

• Conducted experiments using the AuScope geodetic VLBI array in November 2016.
• Developed and implemented a complete process chain: experiment design, observation planning, antenna tracking, correlation, baseline-delay derivation.
• Analyzed data to achieve delay residuals on the order of 10 nanoseconds.

Main Results:

• Successfully executed the first series of VLBI observations for the APOD-A satellite.
• Achieved delay residuals at the 10 ns level, demonstrating the viability of the developed methods.
• Established a robust procedure chain for satellite VLBI observations.

Conclusions:

• The developed VLBI observation and data analysis procedure chain is effective for satellite geodesy.
• This work provides a foundational reference for future geodetic VLBI experiments with satellites.
• The findings will enhance the preparedness of the global VLBI network for upcoming co-location satellite missions.