What’s New in Photutils 1.6?#

Here we highlight some of the new functionality of the 1.6 release. In addition to these major changes, Photutils 1.6 includes a large number of smaller improvements and bug fixes, which are described in the full Changelog.

New centroids available in SourceCatalog#

New centroids were added to the SourceCatalog class, including iteratively-calculated “windowed” centroids and centroids calculated by fitting a 2D quadratic polynomial to the unmasked pixels in the source segment.

The “windowed” centroids are equivalent the SourceExtractors XWIN_IMAGE and YWIN_IMAGE parameters. The new “windowed” centroid properties are:

  • photutils.segmentation.SourceCatalog.centroid_win

  • photutils.segmentation.SourceCatalog.cutout_centroid_win

  • photutils.segmentation.SourceCatalog.xcentroid_win

  • photutils.segmentation.SourceCatalog.ycentroid_win

  • photutils.segmentation.SourceCatalog.sky_centroid_win

The “quadratic” centroids are calculated using centroid_quadratic. The new quadratic centroid properties are:

  • photutils.segmentation.SourceCatalog.centroid_quad

  • photutils.segmentation.SourceCatalog.cutout_centroid_quad

  • photutils.segmentation.SourceCatalog.xcentroid_quad

  • photutils.segmentation.SourceCatalog.ycentroid_quad

  • photutils.segmentation.SourceCatalog.sky_centroid_quad

Slicing a SegmentationImage#

SegmentationImage objects can now be sliced in x and y, generating a new SegmentationImage object.

New ImageDepth class#

A new ImageDepth class was added to compute the limiting fluxes and magnitudes of an image.

ApertureStats#

The ApertureStats class now accepts NDData objects as input.

Progress Bars in SourceCatalog and PSF fitting#

An progress_bar keyword option was added to SourceCatalog to enable progress bars when calculating some properties (e.g., kron_radius, kron_flux, fluxfrac_radius, circular_photometry, centroid_win, centroid_quad).

An option to enable progress bars during PSF fitting was added. To enable it, set progress_bar=True when calling the PSF-fitting object on your data. The progress bar tracks progress over the star groups.

The progress bars require installation of the tqdm optional dependency.

New subshape keyword in PSF fitting#

A new subshape keyword was added to the PSF-fitting classes to define the shape over which the PSF is subtracted when computing the residual image. Previously, the PSF-subtraction region was always defined by the fitshape keyword. By default (and for backwards compatibility), subshape is set to None, which means the fitshape value will be used.