Column Descriptions¶

This page details the columns contained in each output file.

associations¶

Column	Unit	Description
`source_id`	n/a	The database `id` of the source for the association.
`meas_id`	n/a	The database `id` of the measurement for the association.
`d2d`	arcsec	The on-sky separation of the measurement to the source at the iteration stage the association was created.
`dr`	n/a	The de Ruiter radius of the measurement to the source at the iteration stage the association was created. Will be 0 if de Ruiter assocation is not being used.

bands¶

Column	Unit	Description
`id`	n/a	The database `id` of the band.
`name`	n/a	The string name of the band, equal to the frequency value.
`frequency`	MHz	The band central frequency.
`bandwidth`	MHz	The bandwidth of the frequency band, will be 0 if not known.

images¶

Column	Unit	Description
`id`	n/a	The database `id` of the image.
`band_id`	n/a	The database `id` of the associated band.
`skyreg_id`	n/a	The database `id` of the associated sky region.
`measurements_path`	n/a	The system path to the measurements parquet file.
`polarisation`	n/a	The polarisation of the image.
`name`	n/a	The name of the image, taken from the filename.
`path`	n/a	The system path to the image FITS file.
`noise_path`	n/a	The system path to the associated noise image FITS file.
`background_path`	n/a	The system path to the associated background image FITS file.
`datetime`	n/a	The date and time of the observation, read from the FITS header.
`jd`	days	The date and time of the observation in Julian Days.
`duration`	s	The duration of the observation taken from the FITS header, if available.
`ra`	deg	The central Right Ascension coordinate of the image.
`dec`	deg	The central Declination coordinate of the image.
`fov_bmaj`	deg	The estimated major axis field-of-view value - the `radius_pixels` multipled by the major axis pixel size.
`fov_bmin`	deg	The estimated minor axis field-of-view value - the `radius_pixels` multipled by the minor axis pixel size.
`physical_bmaj`	deg	The actual major axis on-sky size - the number of pixels on the major axis multiplied by the major axis pixel size.
`physical_bmin`	deg	The actual minor axis on-sky size - the number of pixels on the minor axis multiplied by the minor axis pixel size.
`radius_pixels`	pixels	Estimated 'diameter' of the useable image area.
`beam_bmaj`	deg	The size of the major axis of the image restoring beam.
`beam_bmin`	deg	The size of the minor axis of the image restoring beam.
`beam_bpa`	deg	The position angle of the image restoring beam.
`rms_median`	mJy/beam	The median RMS value derrived from the RMS map.
`rms_min`	mJy/beam	The minimum RMS value derrived from the RMS map (pixel value).
`rms_max`	mJy/beam	The maximum RMS value derrived from the RMS map (pixel value).

measurements¶

Tip

Some columns are the same as that defined in the Selavy source finder output.

Column	Unit	Description
`island_id`	n/a	The Selavy assigned island_id.
`component_id`	n/a	The Selavy assigned component_id.
`local_rms`	mJy	The rms value at the location of the measurement.
`ra`	deg	The right ascension coordinate of the measurement.
`ra_err`	deg	The error of the right ascension coordinate of the measurement.
`dec`	deg	The declination coordinate of the measurement.
`dec_err`	deg	The error of the declination coordinate of the measurement.
`flux_peak`	mJy/beam	The measured peak flux of the component.
`flux_peak_err`	mJy/beam	The error of the measured peak flux of the component.
`flux_int`	mJy	The measured integrated flux of the component.
`flux_int_err`	mJy	The error of the measured integrated flux of the component.
`bmaj`	arcsec	The major axis size of the fitted Gaussian (FWHM).
`err_bmaj`	deg	The error of the major axis size of the fitted Gaussian (FWHM).
`bmin`	arcsec	The minor axis size of the fitted Gaussian (FWHM).
`err_bmin`	deg	The error of the minor axis size of the fitted Gaussian (FWHM).
`pa`	deg	The position angle of the fitted Gaussian (FWHM).
`err_pa`	deg	The error of the position angle of the fitted Gaussian (FWHM).
`psf_bmaj`	arcsec	The Selavy deconvolved size of the major axis of the fitted Gaussian.
`psf_bmin`	arcsec	The Selavy deconvolved size of the minor axis of the fitted Gaussian.
`psf_pa`	deg	The Selavy deconvolved position angle of the fitted Gaussian.
`flag_c4`	n/a	Selavy flag denoting whether the component is considered formally bad (doesn't meet chi-squared criterion).
`chi_squared_fit`	n/a	The Selavy quality of the fit.
`spectral_index`	n/a	The fitted Selavy spectral index of the component.
`spectral_index_from_TT`	n/a	Selavy flag to denote if the spectral index has been derived from the Taylor-term images (`True`).
`has_siblings`	n/a	Selavy flag to denote whether the component is one of many fitted to the same island.
`image_id`	n/a	The database `id` of the image the measurement is from.
`time`	n/a	The date and time of observation the measurement is from (obtained from the image).
`name`	n/a	The string name of the measurement.
`snr`	n/a	The signal-to-noise ratio of the measurement.
`compactness`	n/a	The compactness of the measurement (`flux_int`/`flux_peak`).
`ew_sys_err`	deg	The systematic right ascension error assigned to the measurement.
`ns_sys_err`	deg	The systematic declination error assigned to the measurement.
`error_radius`	deg	The pipeline estimated error radius of the measurement.
`uncertainty_ew`	deg	Total RA positional error of the measurement.
`uncertainty_ns`	deg	Total Dec positional error of the measurement.
`weight_ew`	deg\(^{-1}\)	The weight of the RA error (1/e).
`weight_ns`	deg\(^{-1}\)	The weight of the Dec error (1/e).
`forced`	n/a	Flag to denote whether the measurement is produced from the forced fitting procedure (`True`).
`flux_int_isl_ratio`	n/a	The ratio of the measurements integrated flux to the total island integrated flux.
`flux_peak_isl_ratio`	n/a	The ratio of the measurements peak flux to the total island peak flux.
`id`	n/a	The database `id` of the measurement.

measurement_pairs¶

Column	Unit	Description
`meas_id_a`	n/a	The database `id` of measurement `a` of the pair.
`meas_id_b`	n/a	The database `id` of measurement `b` of the pair.
`flux_int_a`	mJy	The integrated flux of measurement `a` of the pair.
`flux_int_err_a`	mJy	The error of the integrated flux of measurement `a` of the pair.
`flux_peak_a`	mJy/beam	The peak flux of measurement `a` of the pair.
`flux_peak_err_a`	mJy/beam	The error of the peak flux of measurement `a` of the pair.
`image_name_a`	n/a	The `image name` of measurement `a` of the pair.
`flux_int_b`	mJy	The integrated flux of measurement `b` of the pair.
`flux_int_err_b`	mJy	The error of the integrated flux of measurement `b` of the pair.
`flux_peak_b`	mJy/beam	The peak flux of measurement `b` of the pair.
`flux_peak_err_b`	mJy/beam	The error of the peak flux of measurement `b` of the pair.
`image_name_b`	n/a	The `image name` of measurement `b` of the pair.
`vs_peak`	n/a	The pair \(V_s\) value using the peak flux.
`vs_int`	n/a	The pair \(V_s\) value using the integrated flux.
`m_peak`	n/a	The pair \(m\) value using the peak flux.
`m_int`	n/a	The pair \(m\) value using the integrated flux.
`source_id`	n/a	The database `id` of the source the pair is associated to.
`id`	n/a	The database `id` of the measurement pair.

relations¶

Column	Unit	Description
`from_source_id`	n/a	The database `id` of the first source in the relation pair.
`to_source_id`	n/a	The database `id` of the second source in the relation pair.

skyregions¶

Column	Unit	Description
`id`	n/a	The database `id` of the sky region.
`centre_ra`	deg	The right ascension value of the sky region central coordinate.
`centre_dec`	deg	The declination value of the sky region central coordinate.
`width_ra`	deg	The width of the area covered by the sky region.
`width_dec`	deg	The height of the area covered by the sky region.
`xtr_radius`	deg	The hypotenuse radius of the sky region.
`x`	rad	The central cartesian x coordinate of the sky region.
`y`	rad	The central cartesian y coordinate of the sky region.
`z`	rad	The central cartesian z coordinate of the sky region.

sources¶

Note

The index column of the sources parquet is set to the database id of the source.

Column	Unit	Description
`n_meas`	n/a	The total number of measurements associated to the source (selavy and forced).
`n_meas_sel`	n/a	The total number of selavy measurements associated to the source.
`n_meas_forced`	n/a	The total number of forced measurements associated to the source.
`n_sibl`	n/a	The total number of measurements that have a `has_sibling` value of `True`.
`n_rel`	n/a	The total number of relations the source has.
`wavg_ra`	deg	The weighted average of the Right Ascension of the measurements, that acts as the source position.
`wavg_dec`	deg	The weighted average of the Declination of the measurements, that acts as the source position.
`wavg_uncertainty_ew`	deg	The error of the weighted average right ascension value.
`wavg_uncertainty_ns`	deg	The error of the weighted average declination value.
`new`	n/a	Flag to signify the source is classed as a `new source` (`True`).
`new_high_sigma`	n/a	The largest sigma value a new source would have if it was placed at its location in the previous images it was not detected in. See New Sources for more information. Set to 0 for non-new sources.
`n_neighbour_dist`	deg	The on-sky separation to the nearest source with in the same pipeline run.
`avg_compactness`	n/a	The average compactness value of the associated measurements.
`min_snr`	n/a	The minimum signal-to-noise ratio of the associated measurements.
`max_snr`	n/a	The maximum signal-to-noise ratio of the associated measurements.
`avg_flux_int`	mJy	The average integrated flux value of the measurements associated to the source (inc. forced measurements).
`max_flux_int`	mJy	The maximum integrated flux value of the measurements associated to the source (inc. forced measurements).
`min_flux_int`	mJy	The minimum integrated flux value of the measurements associated to the source (inc. forced measurements).
`avg_flux_peak`	mJy/beam	The average peak flux value of the measurements associated to the source (inc. forced measurements).
`max_flux_peak`	mJy/beam	The maximum peak flux value of the measurements associated to the source (inc. forced measurements).
`min_flux_peak`	mJy/beam	The minimum peak flux value of the measurements associated to the source (inc. forced measurements).
`min_flux_peak_isl_ratio`	n/a	The minimum ratio of the peak flux to the total island peak flux of the measurements associated to the source.
`min_flux_int_isl_ratio`	n/a	The minimum ratio of the integrated flux to the total island integrated flux of the measurements associated to the source.
`v_int`	n/a	The calculated variability \(V\) metric using the integrated flux values. See variability statistics.
`v_peak`	n/a	The calculated variability \(V\) metric using the peak flux values. See variability statistics.
`eta_int`	n/a	The calculated variability \(\eta\) metric using the integrated flux. See variability statistics.
`eta_peak`	n/a	The calculated variability \(\eta\) metric using the peak flux. See variability statistics.
`vs_abs_significant_max_peak`	n/a	The \(\mid V_{s}\mid\) value of the most significant two-epoch pair using the peak fluxes. Will be `0` if no significant pair. See variability statistics.
`m_abs_significant_max_peak`	n/a	The \(\mid m \mid\) value of the most significant two-epoch pair using the peak fluxes. Will be `0` if no significant pair. See variability statistics.
`vs_abs_significant_max_int`	n/a	The \(\mid V_{s}\mid\) value of the most significant two-epoch pair using the integrated fluxes. Will be `0` if no significant pair. See variability statistics.
`m_abs_significant_max_int`	n/a	The \(\mid m \mid\) value of the most significant two-epoch pair using the integrated fluxes. Will be `0` if no significant pair. See variability statistics.

Last update: March 30, 2021
Created: March 18, 2021