This tutorial introduces the EHT-HOPS pipeline — a software suite used to calibrate VLBI data from the Event Horizon Telescope. You’ll learn how raw VLBI data are processed through various stages, from flagging to fringe-fitting and final calibration.
Begin by setting up the necessary environment for running HOPS. We provide setup instructions for common platforms including Ubuntu and macOS. Docker containers are also supported.
Fringe-fitting is one of the core steps in VLBI calibration. This section introduces the logic of multi-band fringe searches and shows how HOPS identifies and corrects for delay and phase offsets.
Once delays and rates are corrected, amplitude calibration aligns flux scales across stations. This step often involves applying system temperature and gain curve data, and accounting for quantization losses.
After calibration in HOPS, you can export the data into FITS-IDI or UVFITS format for further imaging and analysis in CASA or other tools.