LBA observations for project V456 semester 2023OCTS

We propose a sequence of four LBA observations of a Galactic black hole X-ray binary to determine when and how the relativistically-moving jet ejecta are launched from the inner regions of the accretion flow. The first observation, taken in the hard X-ray spectral state prior to the peak of the radio flaring event, will measure the location of the compact core jet. The following three observations, taken during the transition to the soft X-ray spectral state, will measure the proper motions of the relativistically-moving jet ejecta. By extrapolating back to zero-separation from the core location, we will ascertain the exact moment of ejection. Our comparison of X-ray spectral and timing signatures prior to, and following, the ejection will determine the causal sequence of events in the inner accretion flow that leads to the production of relativistic jets.