Arguments

The source detection fitting step has several arguments. These can be specified by the user by passing them to the step in a Python session, or setting them in a parameter file.

• --kernel_fwhm: A parameter for DAOStarFinder: size of Gaussian kernel in

  pixels. By default the FWHM is assumed to be the diffraction limited PSF, given the filter used for this observation.

• --sharplo: A parameter for DAOStarFinder: lower bound for sharpness.

  Default is 0.0.

• --sharphi: A parameter for DAOStarFinder: upper bound for sharpness.

  Default is 1.0.

• --roundlo: A parameter for DAOStarFinder: lower bound for roundness.

  Default is -1.0. A circular source will have a zero roundness. A source extended in x or y will have a negative or positive roundness, respectively.

• --roundhi: A parameter for DAOStarFinder: upper bound for roundness.

  Default is 1.0. A circular source will have a zero roundness. A source extended in x or y will have a negative or positive roundness, respectively.

• --peakmax: A parameter for DAOStarFinder: upper limit on brightest pixel

  in sources. Default is 1000.0.

• --max_sources: The maximum number of sources in the output catalog,

  choosing brightest. Default is None, which will return all detected sources.

• --scalar_threshold: If specified, the absolute detection threshold to be

  used for the entire image. Units are assumed to be the same as input data. One of scalar_threshold, calc_scalar_threshold must be chosen. Default is None.

• --calc_scalar_threshold: If specified, a single scalar threshold will be

  determined for the entire image. This is done by calculating a 2D background image, and using that to determine a single threshold value for the entire image. One of scalar_threshold or calc_scalar_threshold must be chosen. must be chosen. Default is True.

• --snr_threshold: If using calc_threshold_img, the SNR for the threshold

  image. Default is 3.0.

• --bkg_estimator: If using calc_threshold_img, choice of mean, median, or

  mode. Default is median.

• --bkg_boxsize: If using calc_threshold_img size of box in pixels for

  2D background / threshold images and if using calc_threshold_2d, the size of the box used when detecting sources. Default is 9.

• --bkg_sigma: If using calc_threshold_img, n sigma for sigma clipping

  for background calculation. Default is 2.0.

• --bkg_filter_size: If using calc_threshold_img or calc_threshold_2d,

  size of square gaussian kernel for background calculation. Default is 3.

• --save_catalogs: A True/False value that specifies whether to write

  the optional output catalog. Default is False.

• --output_cat_filetype: If save_catalogs is True, file type of output

  catalog from choice of asdf and escv. Catalog will be saved as a numpy array with four dimensions. In order, these represent source ID, x centroid position, y centroid position, and flux.

• --fit_psf: If True, fit a PSF model to each detected source for more precise

  source centroids and fluxes.