Configuration

There are two types of configuration settings: those dedicated purely to measurements, and those related to the source extraction process and to global operations of SourceXtractor++. Measurement settings can be rather complex and require a Python configuration script (see the Measurement section). Global configuration settings may be changed using command-line options (prefixed with a --), however a configuration file is often more convenient for storing settings that do not change from run to run.

Note

Command-line options can be abbreviated, provided that there is no more than one full matching keyword. Example: --config-file=foo.conf may be abbreviated as --conf=foo.conf.

The configuration file

SourceXtractor++ searches for the configuration file at the beginning of a run, starting from system repositories (which makes it possible to apply specific, system-wide configuration settings), to the current repository. Each time it is run, SourceXtractor++ looks for a configuration file. The name of a dedicated configuration files is given with:

$ sourcextractor++ --config-file sepp.config

Creating a configuration file

SourceXtractor++ dumps all parameters with their default values into a configuration files with:

$ sourcextractor++ --dump-default-config > my_sepp.config

Format of the configuration file

Configuration instructions follow the <option> = <value> format. There must be no more than one <option> = <value> instance per line. Comments must be preceded with a #. Boolean parameters are set/unset with 1/0 such as: output-flush-unsorted=1, and the individual parameters of a parameter list are separted with a “,” such as output-properties=SourceIDs,PixelCentroid,WorldCentroid

Configuration parameter list

Here is a complete list of all the configuration parameters known to SourceXtractor++. Please refer to the next sections for a detailed description of their meaning.

Option

Default

Use

Generic options

version

Print version string

help

Produce help message

config-file

Name of a configuration file

log-level

INFO

Log level: FATAL, ERROR, WARN, INFO (default), DEBUG

log-file

Name of a log file

list-output-properties

List the possible output properties for the given input parameters and exit

property-column-mapping-all

Show the columns created for each property

property-column-mapping

Show the columns created for each property, for the given configuration

progress-min-interval

5

Minimal interval to wait before printing a new log entry with the progress report

progress-bar-disable

Disable progress bar display

Auto (Kron) photometry options

auto-kron-factor

2.5

Scale factor for AUTO (Kron) photometry

auto-kron-min-radius

3.5

Minimum radius for AUTO (Kron) photometry

Background modelling

background-cell-size

64

Background mesh cell size to determine a value

smoothing-box-size

3

Background median filter size

Check images

check-image-model-fitting

Path to save the model fitting check image

check-image-residual

Path to save the model fitting residual check image

check-image-background

Path to save the background check image

check-image-variance

Path to save the variance check image

check-image-segmentation

Path to save the segmentation check image

check-image-partition

Path to save the partition check image

check-image-grouping

Path to save the grouping check image

check-image-filtered

Path to save the filtered check image

check-image-thresholded

Path to save the thresholded check image

check-image-auto-aperture

Path to save the auto aperture check image

check-image-aperture

Path to save the aperture check image

check-image-moffat

Path to save the moffat check image

check-image-psf

Path to save the PSF check image

Cleaning

use-cleaning

Enable the cleaning of sources (remove false detections near bright objects)

cleaning-minarea

3

Minimum # of pixels above threshold

Detection image

background-value

Background value to be subtracted from the detection image

detection-threshold

1.5

Detection threshold above the background

segmentation-algorithm

LUTZ

Segmentation algorithm to be used. Currently LUTZ is the only choice

segmentation-disable-filtering

Disables filtering

segmentation-filter

Loads a filter

detection-image

Path to a fits format image to be used as detection image.

detection-image-gain

0

Detection image gain in e-/ADU (0 = infinite gain)

detection-image-flux-scale

Detection image flux scale

detection-image-saturation

Detection image saturation level (0 = no saturation)

detection-image-interpolation

1

Interpolate bad pixels in detection image

detection-image-interpolation-gap

5

Maximum number if pixels to interpolate over

External flag options

flag-image-*

FITS file containing the external flag

flag-type-*

The combination type of the external flag (OR, AND, MIN, MAX, MOST)

Extraction

detect-minarea

3

Minimum # of pixels above threshold

use-attractors-partition

Enables the use of attractors for partitioning

Grouping

grouping-algorithm

NONE

Grouping algorithm to be used (NONE, MOFFAT)

grouping-moffat-threshold

0.02

Threshold used for Moffat grouping.

Magnitude

magnitude-zeropoint

0

Magnitude zero point calibration

Measurement config

python-config-file

Measurements Python configuration file

python-arg

Parameters to pass to Python via sys.argv

Memory usage

tile-memory-limit

512

Maximum memory used for image tiles cache in megabytes

tile-size

256

Image tiles size in pixels

Model Fitting

model-fitting-iterations

1000

Maximum number of iterations allowed for model fitting

Multi-threading

thread-count

4

Number of worker threads (0=disable all multithreading)

Multi-thresholding

partition-multithreshold

Activate multithreshold partitioning

partition-threshold-count

32

of thresholds

partition-min-area

3

Minimum area in pixels to consider partitioning

partition-min-contrast

0.005

Minimum contrast for partitioning

Output configuration

output-catalog-filename

The file to store the output catalog

output-catalog-format

FITS

The format of the output catalog, one of ASCII or FITS

output-properties

PixelCentroid

The output properties to add in the output catalog

Plugin configuration

plugin-directory

Path to a directory that contains the plugins

plugin

Defines a plugin to load (without file extension). Can be used multiple times

Variable PSF

psf-filename

PSF image file (FITS format)

psf-fwhm

Generate a Gaussian PSF with the given full-width half-maximum (in pixels)

psf-pixel-sampling

Generate a Gaussian PSF with the given pixel sampling step size

Weight map

weight-image

Path to a FITS format image to be used as weight image

weight-absolute

0

Is the weight map provided as absolute values or relative to background

weight-type

BACKGROUND

Weight image type (BACKGROUND, RMS, VARIANCE, WEIGHT)

weight-scaling

1

Weight map scaling factor

weight-threshold

Threshold for pixels to be considered bad pixels. In same units as weight map.

weight-usesymmetry

1

Use object symmetry to replace pixels above the weight threshold for photometry