orca.transform.spectrum

Spectrum extraction from visibility data.

Provides functions for generating dynamic spectra and time series from measurement set visibility data. Supports phase shifting, weighting, beam correction, and DFT-based spectrum extraction.

Attributes

logger

N_CHAN

REDIS_URL

REDIS_EXPIRE_S

REDIS_KEY_PREFIX

ROW_NUMS

Functions

gen_spectrum(ms, sourcename[, data_column, timeavg, ...])

Generate spectrum (I,V,XX,XY,YX,YY) from the visibilities; if target_coordinates not assigned, assumes source of interest

dynspec_map(→ List[_SnapshotSpectrum])

Map task for dynamic spectrum generation.

dynspec_reduce(→ None)

Reduce task to combine spectrum data into FITS files.

test_make_dynspec_fits()

Module Contents

orca.transform.spectrum.logger[source]
orca.transform.spectrum.N_CHAN = 192[source]
orca.transform.spectrum.REDIS_URL[source]
orca.transform.spectrum.REDIS_EXPIRE_S = 36000[source]
orca.transform.spectrum.REDIS_KEY_PREFIX = 'spec-'[source]
orca.transform.spectrum.ROW_NUMS = [('LWA-128&LWA-160', 54282), ('LWA-048&LWA-051', 33335), ('LWA-018&LWA-237', 30360),...[source]
orca.transform.spectrum.gen_spectrum(ms: str, sourcename: str, data_column: str = 'CORRECTED_DATA', timeavg: bool = False, outdir: str = None, target_coordinates: str = None, apply_weights: str = None, apply_beam: bool = False)[source]

Generate spectrum (I,V,XX,XY,YX,YY) from the visibilities; if target_coordinates not assigned, assumes source of interest is already at phase center; if apply_weights not assigned, no weights applied.

Parameters:

  • ms – The measurement set.

  • sourcename – The source for which spectrum is being generated. Used for naming output file.

  • data_column – MS data column on which to operate. Default is CORRECTED_DATA.

  • timeavg – Average in time. Default is False.

  • outdir – Path to where output .npz file should be written. Default is path to input ms.

  • apply_weights – Imaging weights npy file (from wsclean-2.5 -store-imaging-weights, IMAGING_WEIGHT_SPECTRUM column).

Returns:

Path to output .npz file containing spectrum.

orca.transform.spectrum.dynspec_map(subband_no: int, scan_no: int, ms: str, bcal: str) → List[_SnapshotSpectrum][source]

Map task for dynamic spectrum generation.

Applies calibration and extracts spectrum data for a single snapshot, storing results in Redis for later reduction.

Parameters:

  • subband_no – Subband index (0-15).

  • scan_no – Scan/timestamp index.

  • ms – Path to the measurement set.

  • bcal – Path to bandpass calibration table.

Returns:

List of _SnapshotSpectrum objects with Redis keys.

orca.transform.spectrum.dynspec_reduce(spectra: Iterable[List[_SnapshotSpectrum]], start_ts: datetime.datetime, out_dir: str) → None[source]

Reduce task to combine spectrum data into FITS files.

Collects spectrum data from Redis, combines across time and frequency, and writes output FITS files with proper WCS headers.

Parameters:

  • spectra – Iterable of spectrum lists from dynspec_map tasks.

  • start_ts – Start timestamp for the observation.

  • out_dir – Output directory for FITS files.

orca.transform.spectrum.test_make_dynspec_fits()[source]