Verification of the Effectiveness of VSOP-2 Phase Referencing with a Newly Developed Simulation Tool, ARIS

TL;DR

This paper evaluates the effectiveness of VSOP-2 space VLBI phase referencing using the ARIS simulation tool, highlighting conditions for successful observations and calibrator availability at different frequencies.

Contribution

It introduces a detailed simulation-based assessment of VSOP-2 phase referencing performance and calibrator availability at multiple frequencies.

Findings

Good phase referencing performance at 8.4GHz under poor conditions

Recommended conditions for 22 and 43GHz observations

High calibrator availability at 8.4GHz, reduced at higher frequencies

Abstract

The next-generation space VLBI mission, VSOP-2, is expected to provide unprecedented spatial resolutions at 8.4, 22, and 43GHz. In this report, phase referencing with VSOP-2 is examined in detail based on a simulation tool called ARIS. The criterion for successful phase referencing was to keep the phase errors below one radian. Simulations with ARIS reveal that phase referencing achieves good performance at 8.4GHz, even under poor tropospheric conditions. At 22 and 43GHz, it is recommended to conduct phase referencing observations under good or typical tropospheric conditions. The satellite is required to have an attitude-switching capability with a one-minute or shorter cycle, and an orbit determination accuracy higher than about 10cm at apogee; the phase referencing calibrators are required to have a signal-to-noise ratio larger than four for a single scan. The probability to find a suitable phase referencing calibrator was estimated by using VLBI surveys. From the viewpoint of calibrator availability, VSOP-2 phase referencing at 8.4GHz is promising. However, the change of finding suitable calibrators at 22 and 43GHz is significantly reduced; it is important to conduct specific investigations for each target at those frequencies.