1. Reference HOPS Calibration Pipeline for millimetre-VLBI Arrays
We present a new version of the EHT-HOPS calibration pipeline (Blackburn et al. 2019), designed to process data from the evolving EHT array, for handling both current and future configurations. This updated pipeline supports the calibration of multiple years of EHT data and similar VLBI arrays, accommodating changes in instrumentation, frequency bands, and array configurations (with and without ALMA). The refactored pipeline improves performance, code integration, and usability, features updated diagnostics, and supports hybrid polarization bases, tested using 2017 M87 data. Planned future developments include complex bandpass and full polarization calibration, parallel processing, and integration with new data formats to generate standardized calibrated data products for all EHT campaigns.
2. Interpol: A Polarized Imaging and Calibration Code for Heterogeneous VLBI Arrays
Very Long Baseline Interferometry (VLBI) has paved the way for groundbreaking astrophysical discoveries, such as black hole jets, planet formation, and imaging of the shadow of a black hole. However, transforming the raw VLBI data into an interpretable image is a formidable challenge. VLBI imaging requires modeling an entire image from a sparse sampling of Fourier components and the complicated instrument response to the incident electric field. While the instrument response and image are traditionally analyzed separately, distinguishing instrumental effects from source structure is complex and non-linear for heterogeneous VLBI arrays such as the EHT or GMVA. In this talk, I will present Interpol, a novel Bayesian simultaneous imaging and calibration algorithm implemented in the VLBI software Comrade. Interpol can reconstruct the full Stokes polarized image and instrumental response for circular, linear, and mixed feed arrays. We demonstrate Interpol on various VLBI arrays, including the VLBA, Event Horizon Telescope, and VLBA sources, demonstrating improved image resolution with fewer image artifacts and discuss its place relative to Polconvert, a common tool used to convert ALMA data from linear to a circular feed basis.