fistar - detecting and characterizing point-like sources
The main purpose of this program is to detect and extract sources (i.e.
star-like objects) from astronomical images. The source detection and
extraction are based on three major steps. First, pixel groups are derived
which are possibly belong to the sources (these preliminary detections are
callad source "candidates"). Second, these candidates are modelled
with some sort of analytic model funcion, in order to derive more precise
centroid coordinates and shape parameters. The last step is to extract the
point-spread function (PSF) for the image, based on the detected and modelled
sources. Basically, the input for this program must be an astronomical image
while the output is the list of detected and extracted sources and their
- -h, --help
- Gives general summary about the command line options.
- --long-help, --help-long
- Gives a detailed list of command line options.
- --wiki-help, --help-wiki,
- Gives a detailed list of command line options in Mediawiki
- --version, --version-short,
- Gives some version information about the program.
- -i, --input <image file>
- Name of input file from which the sources are
- -o, --output <data file>
- Name of the data file where the list of the extracted
sources and their respective characteristics are written.
- -t, --threshold <threshold>
- Detection peak threshold, in ADUs.
- -f, --flux-threshold <flux
- Detection flux threshold, in ADUs.
- --algorithm <algorithm>
- Source cadidate extraction algorithm. It can be
"uplink" (default) or "parabolapeak".
- -p, --prominence <prominence>
- Critical relative prominence parameter used in the
"uplink" algorithm. The default is to use no prominence based
- -r, --shrink <shrink factor>
- Shrink factor applied before star candidate detection. The
image is shrunk by this specific factor and after the detection, the
candidate coordinates are multiplied by this value.
- Do not involve any analitic model funcion during the
derivation of the centroid coordinates and shape parameters, but derive
these from some sort of simple pixel statistics.
- --model <model>[order=<order>]
- Analytic model function used in the second stage of source
extraction. This can be "gauss" (symmetic Gaussian profile),
"elliptic" (assymetric Gaussian profile) and
"deviated" (Gaussian profile multiplied by a polynomial up to
the specified order).
- The number of Levenberg-Marquardt iterations during the
analytic model fit. The fit is done in two substeps, first the symmetric
profile parameters are derived only, which step is followed by the fit for
all of the shape parameters.
- -s, --sort
- Sort the output list of extracted sources by X or Y
coordinate, peak flux (no background level subtracted), profile FWHM, peak
intensity (background level is subtracted), total flux, noise level or
signal-to-noise ratio; respectively.
- --mag-flux <mag>,<flux>
- Magnitude - flux conversion level. The specified magnitude
will be equivalent to the specified flux level.
- -M, --input-mask <image file>
- Input mask file to co-add to the mask of the input image.
Useful for marking pixels to be excluded from source extraction process
beyond the ones which are previously marked in the input image.
- -F, --format <format>
- Comma separated list of format tags, for formatting the
output list of extracted sources. Each row represents an extracted source
while the format specified here defines the quantities listed in each row
of the output file. See "Format tags" for more details.
- An unique identifier for the source (an integer number, in
- Integer X coordinate for the centroid pixel
- Integer Y coordinate for the centroid pixel
- Centroid X coordinate in native coordinate convention.
- Centroid Y coordinate in native coordinate convention.
- Background level
- Peak amplitude
- Gaussian momenum for the stellar profile (S=1/sigma^2)
- plus-shaped momentum for the stellar profile
- cross-shaped momentum for the stellar profile
- sigma parameter for the stellar profile (FWHM is roughly
2.35 * sigma)
- delta (plus-shaped deviance) parameter for the stellar
- kappa (cross-shaped deviance) parameter for the stellar
- full width at half magnitude (FWHM) of the stellar
- ellipticity of the stellar profile
- position angle of the stellar profile
- Total flux of the source
- Noise level of the source
- Signal-to-noise ratio of the detection
- Brightness of the source in magnitudes (see also
- Candidate centroid X coordinate (derived from pixel flux
- Candidate centroid Y coordinate (derived from pixel flux
- Background level for the source candidate
- Peak amplitude of the source candidate
- Maximum intensity on the source cadidate
- Gaussian momenum for the source cadidate, derived from
pixel flux statistics
- plus-shaped momentum for the source cadidate, derived from
pixel flux statistics
- cross-shaped momentum for the source cadidate, derived from
pixel flux statistics
- number of pixels assigned to the detetcted source
- --psf <parameters>
- Comma-separated list of parameters related to the PSF
- subgrid size for the PSF
- halfsize=<half size>
- half-size of the PSF stamp, the full size of the stamp will
always be 2*<half size>+1 and the PSF itself is centered at the
center of the central pixel.
- order of spatial variations in the PSF
- symmetrize the resulting PSF (i.e. fit a symmetric PSF
instead of a normal one)
- use a spline interpolation during the determination of the
- --output-psf <output PSF FITS file>
- Name of the output file where the PSF is saved in FITS
format. The PSF is stored in a 3 dimensional (a.k.a. "data
cube") structure where the z-axis is for the various polynomial
coefficients describing the spatially varied PSF.
- -C, --input-cadidates <cadidate list
- Name of input cadidate list file. If such a file is defined
in the command line, the cadidates are not searched by the build-in
algorithms. Instead, the centroids are read from this file and the pixels
for each object are defined within a certain radius from this centroid
(see -r|--cadidate-radius also). The role of this option is
twofold. First, it is suitable if only some of the sources have to be
modelled with an analytic function; second, PSF determination can be done
only a previously cleaned list of sources, in the case when there might be
contaminating sources too.
- -r, --candidate-radius <radius>
- This option defines a distance, where pixels within this
are assigned to the candidate.
- --col-xy <colx>,<coly>
- Column indices for X and Y centroid coordinates.
Report bugs to <firstname.lastname@example.org>, see also http://fitsh.net/.
Copyright © 1996, 2002, 2004-2008, 2010-2015; Pal, Andras