tweakreg_catalog

The tweakreg_catalog module provides functions for generating catalogs of sources from images.

jwst.tweakreg.tweakreg_catalog.make_tweakreg_catalog(model, kernel_fwhm, snr_threshold, sharplo=0.2, sharphi=1.0, roundlo=- 1.0, roundhi=1.0, brightest=None, peakmax=None)[source]

Create a catalog of point-line sources to be used for image alignment in tweakreg.

Parameters
  • model (ImageModel) – The input ImageModel of a single image. The input image is assumed to be background subtracted.

  • kernel_fwhm (float) – The full-width at half-maximum (FWHM) of the 2D Gaussian kernel used to filter the image before thresholding. Filtering the image will smooth the noise and maximize detectability of objects with a shape similar to the kernel.

  • snr_threshold (float) – The signal-to-noise ratio per pixel above the background for which to consider a pixel as possibly being part of a source.

  • sharplo (float, optional) – The lower bound on sharpness for object detection.

  • sharphi (float, optional) – The upper bound on sharpness for object detection.

  • roundlo (float, optional) – The lower bound on roundess for object detection.

  • roundhi (float, optional) – The upper bound on roundess for object detection.

  • brightest (int, None, optional) – Number of brightest objects to keep after sorting the full object list. If brightest is set to None, all objects will be selected.

  • peakmax (float, None, optional) –

    Maximum peak pixel value in an object. Only objects whose peak pixel values are strictly smaller than peakmax will be selected. This may be used to exclude saturated sources. By default, when peakmax is set to None, all objects will be selected.

    Warning

    DAOStarFinder automatically excludes objects whose peak pixel values are negative. Therefore, setting peakmax to a non-positive value would result in exclusion of all objects.

Returns

catalog – An astropy Table containing the source catalog.

Return type

Table