ivis.utils.dcasacore

Measurement Set I/O Utilities

This module provides tools for extracting and filtering visibility data from radio interferometric Measurement Sets (MS), either in serial or parallel mode. It supports both casacore.tables and optional dask-ms backends.

Functions

• phasecenter_casacore(ms)

• read_channel_casacore(...)

• readmsl(...) / readmsl_no_parallel(...)

Returned data are stored in a VisData dataclass containing visibility coordinates, data, noise estimates, beam indices, and sky positions.

Author: Antoine Marchal

Functions

phasecenter_casacore(ms)	Extracts the phase center (RA/Dec) from the FIELD table of a Measurement Set.
phasecenter_dask(ms)	(Dask version) Extracts the phase center from FIELD table of MS using dask-ms.
process_ms(ms, uvmin, uvmax, ...)	Process a single MS file and return the extracted data.
read_channel_casacore(ms_path, uvmin, uvmax, ...)	Read a single frequency channel from a Measurement Set using casacore.tables.
readms_dask(ms_path, uvmin, uvmax, chunks, ...)	(Obsolete) Reads a single channel from an MS using dask-ms and filters baselines.
readmsl(msl, uvmin, uvmax, target_frequency, ...)	Parallelized version of readmsl using ProcessPoolExecutor.
readmsl_no_parallel(msl, uvmin, uvmax, ...)

Classes

VisData(uu, vv, ww, sigma, data, beam, ...)

class ivis.utils.dcasacore.VisData(uu, vv, ww, sigma, data, beam, coords, frequency, velocity)

Bases: object

beam: ndarray

coords: ndarray

data: ndarray

frequency: ndarray

sigma: ndarray

uu: ndarray

velocity: ndarray

vv: ndarray

ww: ndarray

ivis.utils.dcasacore.phasecenter_casacore(ms)

Extracts the phase center (RA/Dec) from the FIELD table of a Measurement Set.

ivis.utils.dcasacore.phasecenter_dask(ms)

(Dask version) Extracts the phase center from FIELD table of MS using dask-ms.

ivis.utils.dcasacore.process_ms(ms, uvmin, uvmax, target_frequency, target_channel, k)

Process a single MS file and return the extracted data.

ivis.utils.dcasacore.read_channel_casacore(ms_path, uvmin, uvmax, target_frequency, target_channel)

Read a single frequency channel from a Measurement Set using casacore.tables.

Parameters:

• ms_path (str) – Path to the Measurement Set directory.

• uvmin (float) – Minimum baseline length in wavelengths.

• uvmax (float) – Maximum baseline length in wavelengths.

• target_frequency (Quantity) – Target frequency (in Hz).

• target_channel (int) – Index of the desired frequency channel.

Returns:

• freq (float) – Extracted channel frequency (Hz).

• vel (Quantity) – Computed velocity in the LSRK frame.

• uvw_lambda (ndarray) – (N, 3) array of baseline vectors in units of lambda.

• sigma_i (ndarray) – Estimated noise.

• stokes_i (ndarray) – Stokes I visibilities.

• ra_hms, dec_dms (str) – RA/Dec of phase center in HMS/DMS string format.

ivis.utils.dcasacore.readms_dask(ms_path, uvmin, uvmax, chunks, target_frequency)

(Obsolete) Reads a single channel from an MS using dask-ms and filters baselines.

ivis.utils.dcasacore.readmsl(msl, uvmin, uvmax, target_frequency, target_channel, n_workers)

Parallelized version of readmsl using ProcessPoolExecutor.

ivis.utils.dcasacore.readmsl_no_parallel(msl, uvmin, uvmax, target_frequency, target_channel)