potpyri.primitives.solve_wcs

WCS solution using astrometry.net and Gaia DR3 alignment.

Provides coarse solution via solve-field and fine alignment by matching detected sources to Gaia. Writes RADISP/DEDISP and updated WCS to FITS. Authors: Kerry Paterson, Charlie Kilpatrick.

Functions

clean_up_astrometry(directory, file, exten)

Remove astrometry.net temporary files (.axy, .corr, .solved, .wcs, etc.).

fine_align_wcs(file, tel[, catalog, radius, ...])

Refine WCS by matching detections to a reference catalog (fine alignment).

get_fine_align_reference_catalog(input_file)

Query the configured reference catalog for fine WCS alignment.

solve_astrometry(file, tel, binn, paths[, ...])

Run astrometry.net (solve-field) to get coarse WCS; optionally use custom index.

validate_existing_wcs_header(header)

Check that a FITS header already defines a usable celestial WCS.
potpyri.primitives.solve_wcs.clean_up_astrometry(directory, file, exten)[source]

Remove astrometry.net temporary files (.axy, .corr, .solved, .wcs, etc.).

Parameters:

  • directory (str) – Directory containing the files.

  • file (str) – Base filename (with extension); exten is replaced to form temp names.

  • exten (str) – File extension (e.g. ‘.fits’) to replace with .axy, .corr, etc.

Return type:

None

potpyri.primitives.solve_wcs.fine_align_wcs(file, tel, catalog='gaia', radius=0.5, max_search_radius=<Quantity 5. arcsec>, save_centroids=False, min_cat_match=7, log=None)[source]

Refine WCS by matching detections to a reference catalog (fine alignment).

Parameters:

  • file (str) – Path to FITS file with WCS (e.g. after solve_astrometry).

  • tel (Instrument) – Instrument instance.

  • catalog (str, optional) – Reference catalog: gaia (default), panstarrs, sdss, legacy, twomass, or skymapper. See potpyri.utils.catalogs.FINE_ALIGN_CATALOG_CHOICES.

  • radius (float, optional) – Catalog query half-width in degrees. Default is 0.5.

  • max_search_radius (astropy.units.Quantity, optional) – Match radius between detections and catalog positions. Default is 5 arcsec.

  • save_centroids (bool, optional) – If True, save centroid table. Default is False.

  • min_cat_match (int, optional) – Minimum number of in-frame catalog sources required before matching. Default is 7.

  • log (ColoredLogger, optional) – Logger for progress.

Returns:

True if alignment succeeded and WCS was updated, False otherwise.

Return type:

bool

potpyri.primitives.solve_wcs.get_fine_align_reference_catalog(input_file, catalog='gaia', radius_deg=0.5, log=None)[source]

Query the configured reference catalog for fine WCS alignment.

Parameters:

  • input_file (str) – Path to FITS file; primary header used for field center.

  • catalog (str, optional) – Catalog key (see potpyri.utils.catalogs.FINE_ALIGN_CATALOG_CHOICES). Default is 'gaia'.

  • radius_deg (float, optional) – Half-width of the VizieR query box in degrees. Default 0.5.

  • log (ColoredLogger, optional) – Logger.

Returns:

Table with RA_ICRS, DE_ICRS in degrees, None if empty or query failed, False if field center could not be parsed from the header.

Return type:

astropy.table.Table or None or False

potpyri.primitives.solve_wcs.solve_astrometry(file, tel, binn, paths, radius=0.5, replace=True, shift_only=False, index=None, log=None)[source]

Run astrometry.net (solve-field) to get coarse WCS; optionally use custom index.

Parameters:

  • file (str) – Path to FITS file to solve.

  • tel (Instrument) – Instrument instance (name, get_pixscale).

  • binn (str) – Binning string (e.g. ‘22’) for pixel scale.

  • paths (dict) – Paths dict (source_extractor key for solve-field).

  • radius (float, optional) – Search radius in degrees. Default is 0.5.

  • replace (bool, optional) – If True, write WCS into original file; else write .solved.fits.

  • shift_only (bool, optional) – If True, only update CRPIX/CRVAL. Default is False.

  • index (str, optional) – Path to custom index file or directory for solve-field.

  • log (ColoredLogger, optional) – Logger for progress.

Returns:

True if solve succeeded, False otherwise.

Return type:

bool

potpyri.primitives.solve_wcs.validate_existing_wcs_header(header)[source]

Check that a FITS header already defines a usable celestial WCS.

Requires CTYPE1, CTYPE2, CRVAL1, CRVAL2, CRPIX1, CRPIX2, and a linear celestial transform via either the CD matrix (CD1_1..CD2_2) or CDELT1 and CDELT2 (optionally with PC matrix). Confirms astropy.wcs.WCS can parse the header and evaluate pixel-to-world for one point.

Parameters:

header (astropy.io.fits.Header) – Header to validate (typically primary HDU).

Returns:

(ok, reason) where ok is True if validation passed; reason is an empty string on success, or a short message on failure.

Return type:

tuple