location_from_wcs

jwst.extract_1d.source_location.location_from_wcs(input_model, slit, make_trace=True)[source]

Get the cross-dispersion location of the spectrum, based on the WCS.

None values will be returned if there was insufficient information available, e.g. if the wavelength attribute or wcs function is not defined.

Parameters:

  • input_model (DataModel) – The input science model containing metadata information.

  • slit (DataModel or None) – One slit from a MultiSlitModel (or similar), or None. The WCS and target coordinates will be retrieved from slit unless slit is None. In that case, they will be retrieved from input_model.

  • make_trace (bool, optional) – If True, the source position will be calculated for each dispersion element and returned in trace. If False, None is returned.

Returns:

  • middle (int or None) – Pixel coordinate in the dispersion direction within the 2-D cutout (or the entire input image) at the middle of the WCS bounding box. This is the point at which to determine the nominal extraction location, in case it varies along the spectrum. The offset will then be the difference between location (below) and the nominal location.

  • middle_wl (float or None) – The wavelength at pixel middle.

  • location (float or None) – Pixel coordinate in the cross-dispersion direction within the spectral image that is at the planned target location. The spectral extraction region should be centered here.

  • trace (ndarray or None) – An array of source positions, one per dispersion element, corresponding to the location at each point in the wavelength array. If the input data is resampled, the trace corresponds directly to the location. If the trace could not be generated, or make_trace is False, None is returned.