Step 2 Overview & Scripts

In this step, we align the phase centers of all execution blocks to a common phase center, using the source’s continuum morphology and assuming it is not variable in time.

Scripts for Step 2 - Phase alignment:

• step2_phase_alignment.py # main script (using modular CASA)

• dictionary_data.py # loads data_dict

• alignment.py # exoALMA visibility alignment functions

• example_alignment_usage.py # exoALMA alignment example

Align Long-Baseline Execution Blocks: We selected one of the long-baseline execution blocks to serve as the reference EB, to whose phase center all other EBs are aligned. The LB1 execution block (phase center: J2000 04:55:45.854900 +30.33.03.73320; observed 2022-07-17) was chosen as the reference EB as it was observed in the most favorable weather conditions and had the highest SNR in the initial images.

Align Short-Baseline Execution Blocks: This procedure was repeated to align the two short-baseline EBs to the common phase center, this time taking the aligned concatenated long-baseline dataset as the reference in order to maximize the potential for overlap of uv points in the common grid. We then concatenated the shifted short-baseline EBs into a single phase-aligned short-baseline dataset.

Summary of Phase Shifts: A summary of the applied phase shifts.