dsa110-voltage-imaging

Interferometric localization of DSA-110 FRBs from M8-era raw voltage dumps.

Correlates the candidate archive's voltage fragments with the dsa110-bbproc toolkit (pre-correlation dedispersion), builds calibrated measurement sets, ties the astrometry to RFC VLBI calibrators, and produces a corrected FRB position.

The pre-M8 (T3-era) version of this repo — toolkit_dev correlator, T2_<cand>.json metadata, Level2/calibration layout, batch.bash — is preserved on the legacy branch.

Layout

• dsavim/ — python package. metadata.py reads the M8 candidate archive (/dataz/dsa110/candidates/<name>/: Level3/<name>.json C2 record, Level2/voltages/ fragments + manifests, filterbank/ provenance, calibration/ ±2 h correlator HDF5s hard-linked by C3) into a Burst object. voltages_to_ms.py, generate_uvh5.py, uvh5_to_ms.py do the correlation and MS conversion.
• scripts/run_localization.py — the driver (pythonized batch.bash).
• scripts/voltages_to_ms.py, create_ms.py, bp_gain_cal.py, create_all_icrs.py, calibrate_image_icrs.py — pipeline stages invoked by the driver (each runnable standalone).
• notebooks/localize.ipynb — the localization analysis, run after the driver.

Usage (h23, casa38 environment)

conda activate casa38
cd scripts
python run_localization.py <candname>

The driver measures the burst time bin itself (a coherent filterbank formed with pre-correlation dedispersion), derives the science-MS offsets, and runs every stage through the wsclean images; see python run_localization.py -h for stage selection and overrides. Key options:

• --dm — refine beyond the search's dm_median.
• --ntint — science-MS integration (native 32.768 µs samples; default 512).
• --bpcal-source — bandpass calibrator, by VLA-calibrator-list name (default 2253+161 = 3C454.3). The latest per-transit MS from the realtime calibration system (/dataz/dsa110/operations/calibration) is copied in; if none exists it is built from the /dataz/dsa110/operations/correlator HDF5s. Or pass an existing MS with --bpcal-ms.
• --bpcal-flux-jy, --refant — calibration knobs (defaults 15 Jy, ant 104).

Outputs land in /media/ubuntu/ssd/localization_processing/<candname>/, including localization_run.json (all derived parameters). RFC calibrator counts are limited to 10 everywhere.

Then open notebooks/localize.ipynb, set trigname, and run all cells for the bandpass QC, NVSS astrometry check, VLBI offset fit, and the corrected FRB position.