Step Arguments

The source_catalog step has the following optional arguments.

General parameters:

--suffix (str, default=’cat’)

File name suffix to use for the output catalog file.

Aperture photometry parameters:

--aperture_ee1 (int, default=30)

Value of the smallest aperture encircled energy.

--aperture_ee2 (int, default=50)

Value of the middle aperture encircled energy.

--aperture_ee3 (int, default=70)

Value of the largest aperture encircled energy.

--ci1_star_threshold (float, default=2.0)

The threshold compared to the concentration index calculated from aperture_ee1 and aperture_ee2 that is used to determine whether a source is a star. Sources must meet the criteria of both ci1_star_threshold and ci2_star_threshold to be considered a star.

--ci2_star_threshold (float, default=1.8)

The threshold compared to the concentration index calculated from aperture_ee2 and aperture_ee3 that is used to determine whether a source is a star. Sources must meet the criteria of both ci1_star_threshold and ci2_star_threshold to be considered a star.

General source finding parameters:

--starfinder (str, default=’segmentation’)

The source detection algorithm to use. Allowed values: 'iraf', 'dao', 'segmentation'.

--snr_threshold (float, default=3.0)

SNR threshold above the background. Required for all star finders.

--bkg_boxsize (int, default=1000)

A positive value indicating the background mesh box size in pixels.

--kernel_fwhm (float, default=2.0)

The Gaussian kernel FWHM in pixels.

Additional source finding parameters for “segmentation”:

--npixels (int, default=25)

The minimum number of connected pixels that comprises a segment.

--connectivity (int, default=8)

The connectivity defining the neighborhood of a pixel. Options are 4, i.e., connected pixels touch along edges, or 8, i.e, connected pixels touch along edges or corners.

--nlevels (int, default=32)

The number of multi-thresholding levels for deblending.

--contrast (float, default=0.001)

The fraction of total source flux an object must have to be deblended.

--multithresh_mode (str, default=’exponential’)

The multi-thresholding mode. Allowed values: 'exponential', 'linear', 'sinh'.

--localbkg_width (int, default=0)

The width of rectangular annulus used to compute local background around each source. If set to 0, then local background will not be subtracted.

--apermask_method (str, default=’correct’)

The method used to handle neighboring sources when performing aperture photometry. Allowed values: 'correct', 'mask', 'none'.

--kron_params (tuple of float, default=None)

The parameters defining Kron aperture. If None, the parameters (2.5, 1.4, 0.0) are used.

--deblend (bool, default=True)

Indicator for whether to deblend sources.

Additional source finding parameters for “dao” and “iraf”:

--minsep_fwhm (float, default=0.0)

The minimum separation between detected objects in units of number of FWHMs.

--sigma_radius (float, default=1.5)

The truncation radius of the Gaussian kernel in units of number of FWHMs.

--sharplo (float, default=0.5)

The lower bound on sharpness for object detection.

--sharphi (float, default=2.0)

The upper bound on sharpness for object detection.

--roundlo (float, default=0.0)

The lower bound on roundness for object detection.

--roundhi (float, default=0.2)

The upper bound on roundness for object detection.

--brightest (int, default=200)

A positive value indicating the number of brightest objects to keep. If None, keep all objects above the threshold.

--peakmax (float, default=None)

A value used to filter out objects with pixel values >= peakmax.

Warning

Different source finding algorithms have different values for the sharplo, sharphi, roundlo, and roundhi parameters. These parameters should be adjusted to match the algorithm selected by the starfinder parameter. See documentation for IRAFStarFinder and DAOStarFinder.