public documents.sextractor_doc

\section{The \index{configuration file} configuration file}

\label{chap:configfile}

Each time it is run, {\sc SExtractor} looks for a \index{configuration file} configuration file. If no

\index{configuration file} configuration file is specified in the command-line, it is assumed to

be called ``{\tt default.sex}'' and to reside in the current

directory. If no \index{configuration file} configuration file is found, {\sc SExtractor} will use its own

internal default configuration.

\subsection{Creating a \index{configuration file} configuration file}

{\sc SExtractor} can generate an ASCII dump of its internal default

configuration, using the ``{\tt -d}'' option. By redirecting the standard

output of {\sc SExtractor} to a file, one creates a \index{configuration file} configuration file that

can easily be modified afterwards:

{\tt \% sex -d > default.sex}

A more extensive dump with less commonly used parameters can be generated by

using the ``{\tt -dd}'' option.

\subsection{Format of the \index{configuration file} configuration file}

The format is ASCII. There must be only one parameter set per line,

following the form:

~~~~ {\em Config-parameter ~~~~ Value(s)}

Extra spaces or linefeeds are ignored. Comments must begin with a ``\#''

and end with a linefeed. Values can be of different

types: strings (can be enclosed between double quotes), floats, integers, keywords or Boolean

({\tt Y/y} or {\tt N/n}). Some parameters accept zero or several values, which must then be

separated by commas.

Integers can be given as decimals, in octal form (preceded by digit {\tt O}), or in hexadecimal

(preceded by {\tt 0x}). The hexadecimal format is particularly convenient for writing multiplexed

bit values such as binary masks. Environment variables, written as {\tt \$HOME} or {\tt \$\{HOME\}}

are expanded, and not only for string parameters. Some parameters are assigned default values in

{\sc SExtractor} and can therefore be omitted from the \index{configuration file} configuration file; they are listed in

\S\ref{chap:config}.

\subsection{Configuration parameter list}

\label{chap:config}

Here is a complete list of all the {\em configuration} parameters known to {\sc SExtractor}.

Many of them should be used with their default values. Please refer to the next sections for a

detailed description of their \index{mean} meaning.

% \begin{tabular}{lllp{2.5in}}

\begin{tabbing}

KKKKKKKKKKKKKK \= AAAAAAAAAAAAA \= VVVVVVVVVVVV \= \`TTTTTTTTTTTT \kill

\parhead{Parameter              }{ default }{ type }

\parlist{ Description}\\

%\hline

\parhead{{\tt ANALYSIS\_THRESH}   }{ {\tt 1.5} }{ {\em floats}\ $(n \le 2)$ }

\parlist{ Threshold (in surface brightness) at

        which {\tt CLASS\_STAR} and {FWHM\_} \gam{why underscore?} operate. 1

        argument: relative to Background RMS (before filtering).

        2 arguments: surface magnitude $\mu$ ($\rm mag\,arcsec^{-2}$), Zero-point (mag).}\\

\parhead{{\tt ASSOC\_DATA}      }{ {\tt 2,3,4} }{ {\em integers}\ $(n\le

  32)$}

\parlist{ \# of the columns in the

        {\tt ASSOC} file that will be copied to the catalogue output.}\\

\parhead{{\tt ASSOC\_NAME}      }{ {\tt sky.list} }{ {\em string}          }

\parlist{ Name of the {\tt ASSOC} ASCII file.}\\

\parhead{{\tt ASSOC\_PARAMS}    }{ {\tt 2,3,4} }{ {\em integers}\ $(2 \le n

  \le 3)$}

\parlist{ \# of the columns in the {\tt ASSOC} file that will be used as coordinates

                                                            and weight for cross-matching.}\\

\parhead{{\tt ASSOC\_RADIUS}    }{ {\tt 2.0} }{ {\em float}                }

\parlist{ Search radius (in pixels) for {\tt ASSOC}.}\\

\parhead{{\tt ASSOC\_TYPE}      }{ {\tt MAG\_SUM} }{ {\em keyword}         }

\parlist{ Method for cross-matching in {\tt ASSOC}:}\\

\pararg {\tt FIRST}          { -- keep values corresponding to the first match found,}

\pararg{                                  \tt NEAREST}        {values corresponding to the nearest match found,}

\pararg{                                  \tt MEAN}           {weighted-average values,}

\pararg{                                  \tt MAG\_MEAN}      {exponentially weighted-average values,}

\pararg{                                  \tt SUM}            {sum values,}

\pararg{                                  \tt MAG\_SUM}       {exponentially sum values,}

\pararg{                                  \tt MIN}            {keep values corresponding to the match with minimum weight,}

\pararg{                                  \tt MAX}            {keep values corresponding to the match with maximum weight.}

\parhead{{\tt ASSOCSELEC\_TYPE} }{ {\tt MATCHED}   }{ {\em keyword}  }

\parlist{ What sources are printed in the output catalogue in case of {\tt ASSOC}:}\\

\pararg{                                  \tt ALL}            {all detections,}

\pararg{                                  \tt MATCHED}        {only matched detections,}

\pararg{                                  \tt -MATCHED}       {only detections that were not matched.}

\parhead{{\tt BACK\_FILTERSIZE} }{ {\tt 3} }{ {\em integers}\ $(n \le 2)$ }

\parlist{ Size, or Width,Height (in background meshes) of the background-filtering mask.}\\

\parhead{{\tt BACK\_SIZE}       }{ {\tt 64} }{ {\em integers}\ $(n \le 2)$ }

\parlist{ Size, or Width,Height (in pixels) of a background mesh.}\\

\parhead{{\tt BACK\_TYPE}       }{ {\tt AUTO} }{ {\em keywords}\ $(n \le 2)$}

\parlist{ What background is subtracted from the \index{image} images:}\\

\pararg{                            \tt AUTO}            {the internal,

                       automatically interpolated \index{background map} background map,}

\pararg{                            \tt MANUAL}             {a user-supplied constant value provided in {\tt BACK\_VALUE}.}

\parhead{{\tt BACK\_VALUE} }{ {\tt 0.0,0.0} }{ {\em floats}\ $(n \le 2)$ }

\parlist{ in {\tt BACK\_TYPE MANUAL} \index{mode} mode, the constant value to be subtracted

                                                                from the \index{image} images.}\\

\parhead{{\tt BACKPHOTO\_THICK} }{ {\tt 24}  }{ {\em integer}           }

\parlist{ Thickness (in pixels) of the background {\tt LOCAL} annulus.}\\

\parhead{{\tt BACKPHOTO\_TYPE}  }{ {\tt GLOBAL} }{ {\em keyword}        }

\parlist{ Background used to compute magnitudes:}\\

\pararg{                            \tt GLOBAL}            {taken directly from the \index{background map} background map,}

\pararg{                            \tt LOCAL}             {recomputed in a ``rectangular annulus'' around the object.}

\parhead{{\tt CATALOG\_NAME}    }{ {\tt test.cat} }{ {\em string}

}

\parlist{ Name of the output catalogue. If the name ``{\tt STDOUT}'' is given and

                                                         {\tt CATALOG\_TYPE} is set to {\tt ASCII}, {\tt ASCII\_HEAD}, {\tt ASCII\_SKYCAT}, or {\tt ASCII\_VOTABLE}, the catalogue will be piped to the standard output ({\em stdout})}\\

\parhead{{\tt CATALOG\_TYPE}    }{ --- }{ {\em keyword} }

\parlist{ Format of output catalogue (note

that ASCII\* is space and time consuming):}\\

\pararg{                            \tt ASCII}   {ASCII table,}

\pararg{                            \tt ASCII\_HEAD}   {as {\tt ASCII},

preceded by a header containing information about the content,}

\pararg{                            \tt ASCII\_SKYCAT} {SkyCat ASCII format (WCS coordinates required),}

\pararg{                            \tt ASCII\_VOTABLE} {XML-VOTable format, together with meta-data,}

\pararg{                            \tt FITS\_1.0}     {FITS format as in {\sc SExtractor} 1,}

\pararg{                            \tt FITS\_LDAC}    {FITS ``LDAC'' format (the original \index{image} image header is copied).}

\parhead{{\tt CHECKIMAGE\_NAME} }{ {\tt check.fits} }{ {\em strings} $(n \le  16)$  }

\parlist{ File name for each ``check-image''.}\\

\parhead{{\tt CHECKIMAGE\_TYPE} }{ {\tt NONE} }{ {\em keywords} $(n \le 16)$}

\parlist{ Type of information in the ``check-images'':}\\

\pararg{                            \tt NONE}         {no \index{check-image} check-image,}

\pararg{                            \tt IDENTICAL}    {identical to input \index{image} image (useful for converting formats),}

\pararg{                            \tt BACKGROUND}   {full-resolution interpolated \index{background map} background map,}

\pararg{                            \tt BACKGROUND\_RMS} {full-resolution interpolated background noise map,}

\pararg{                            \tt MINIBACKGROUND} {low-resolution \index{background map} background map,}

\pararg{                            \tt MINIBACK\_RMS} {low-resolution background noise map,}

\pararg{                            \tt -BACKGROUND}  {background-subtracted \index{image} image,}

\pararg{                            \tt FILTERED}     {background-subtracted filtered \index{image} image (requires {\tt FILTER = Y}),}

\pararg{                            \tt OBJECTS}      {detected objects,}

\pararg{                            \tt -OBJECTS}     {background-subtracted \index{image} image with detected objects blanked,}

\pararg{                            \tt APERTURES}    {{\tt MAG\_APER} and {\tt MAG\_AUTO} integration limits,}

\pararg{                            \tt SEGMENTATION} {display patches corresponding to pixels attributed to each object.}

\parhead{{\tt CLEAN}            }{ {\tt Y} }{ {\em boolean}      }

\parlist{ If true,  the

catalogue is ``cleaned'' (\S\ref{chap:clean}) before being written to disk.}\\

\parhead{{\tt CLEAN\_PARAM}     }{ {\tt 1.0} }{ {\em float}        }

\parlist{ Efficiency of ``cleaning''.}\\

\parhead{{\tt DEBLEND\_MINCONT} }{ {\tt 0.005} }{ {\em float}        }

\parlist{ Minimum contrast parameter for \index{deblending} deblending.}\\

\parhead{{\tt DEBLEND\_NTHRESH} }{ {\tt 32} }{ {\em integer}      }

\parlist{ Number of \index{deblending} deblending sub-thresholds.}\\

\parhead{{\tt DETECT\_MINAREA}  }{ {\tt 5} }{ {\em integer}      }

\parlist{ Minimum number of pixels above \index{threshold} threshold triggering detection.}\\

\parhead{{\tt DETECT\_MAXAREA}  }{ {\tt 0} }{ {\em integer}      }

\parlist{ Maximum number of pixels

above \index{threshold} threshold triggering detection (0 for infinite).}\\

\parhead{{\tt DETECT\_THRESH}   }{ {\tt 1.5} }{ {\em floats}\ $(n \le 2)$ }

\parlist{ Detection \index{threshold} threshold. 1 argument: (ADUs or relative to Background RMS, see

                                                       {\tt THRESH\_TYPE}). 2

                                                       arguments: $\mu$ ($\rm

                                                       mag\,arcsec^{-2}$), Zero-point (mag).}\\

\parhead{{\tt DETECT\_TYPE}     }{  {\tt \index{CCD} CCD} }{ {\em keyword} }

\parlist{ Type of device that produced the \index{image} image:}\\

\pararg{                            \tt \index{CCD} CCD}          {linear detector like CCDs or \index{NICMOS} NICMOS,}

\pararg{                            \tt PHOTO}        {photographic scan.}

\parhead{{\tt FILTER}           }{ --- }{ {\em boolean}      }

\parlist{ If true, filtering is applied to the data before extraction.}\\

\parhead{{\tt FILTER\_NAME}     }{ --- }{ {\em string}       }

\parlist{ Name of the file containing the filter definition.}\\

\parhead{{\tt FILTER\_THRESH}   }{     }{ {\em floats}\ $(n \le 2)$ }

\parlist{ Lower and higher \index{threshold} thresholds (in background \index{standard deviation} standard deviations) for a pixel

                                                          to be considered in filtering (used for retina-filtering only).}\\

\parhead{{\tt FITS\_UNSIGNED}   }{  {\tt N}  }{ {\em boolean} }

\parlist{ Force 16-bit FITS input data to be interpreted as unsigned integers.}\\

\parhead{{\tt FLAG\_IMAGE}      }{ {\tt flag.fits} }{ {\em strings}\ $(n \le  4)$ }

\parlist{ File name(s) of the ``flag-image(s)''.}\\

\parhead{{\tt FLAG\_TYPE}       }{ {\tt OR} }{ {\em keyword} }

\parlist{ Combination method for \index{flags} flags on the same object:}\\

\pararg{                                 \tt OR}      {arithmetical OR,}

\pararg{                                 \tt AND}     {arithmetical AND,}

\pararg{                                 \tt MIN}     {minimum of all flag values,}

\pararg{                                 \tt MAX}     {maximum of all flag values,}

\pararg{                                 \tt MOST}    {most common flag value.}

\parhead{{\tt GAIN}             }{     }{ {\em float}        }

\parlist{ ``Gain'' (conversion factor in $e^-/\mbox{ADU}$) used for error estimates

                                                    of {\tt \index{CCD} CCD} magnitudes .}\\

\parhead{{\tt INTERP\_MAXXLAG}  }{ {\tt 16} }{ {\em integers}\ $(n \le 2)$ }

\parlist{ Maximum $x$ gap (in pixels) allowed in interpolating the input \index{image} image(s).}\\

\parhead{{\tt INTERP\_MAXYLAG}  }{ {\tt 16} }{ {\em integers}\ $(n \le 2)$ }

\parlist{ Maximum $y$ gap (in pixels) allowed in interpolating the input \index{image} image(s).}\\

\parhead{{\tt INTERP\_TYPE}     }{ {\tt ALL} }{ {\em keywords}\ $(n \le 2)$ }

\parlist{

Interpolation method from the \index{variance map} variance map(s) (or \index{weight map} weight map(s)):}\\

\pararg{                                   \tt NONE}  {no \index{interpolation} interpolation,}

\pararg{                                   \tt VAR\_ONLY} {interpolate only the \index{variance map} variance map (detection \index{threshold} threshold),}

\pararg{                                   \tt ALL} {interpolate both the \index{variance map} variance map and the \index{image} image itself.}

\parhead{{\tt MAG\_GAMMA}       }{     }{ {\em float} }

\parlist{ $\gamma$ of the emulsion (takes effect in {\tt PHOTO} \index{mode} mode only).}\\

\parhead{{\tt MAG\_ZEROPOINT}   }{     }{ {\em float} }

\parlist{ Zero-point offset to be applied to magnitudes.}\\

\parhead{{\tt MASK\_TYPE}       }{ {\tt CORRECT} }{ {\em keyword} }

\parlist{ Method of ``masking'' of \index{neighbour} \index{neighbours} neighbours for photometry:}\\

\pararg{                                   \tt NONE}  {no \index{masking} masking,}

\pararg{                                   \tt BLANK} {put detected pixels belonging to \index{neighbour} \index{neighbours} neighbours to zero,}

\pararg{                                   \tt CORRECT} {replace by values of pixels symetric with respect to the source center.}

\parhead{{\tt MEMORY\_BUFSIZE}  }{ {\tt 1024} }{ {\em integer} }

\parlist{ Number of scan-lines in the \index{image} image-buffer. Multiply by 4 the frame width to

                                            get equivalent \index{memory} memory space in bytes.}\\

\parhead{{\tt MEMORY\_OBJSTACK} }{ {\tt 3000} }{ {\em integer} }

\parlist{ Maximum number of objects that the object-stack can contain. Multiply by 300 to get

                                            equivalent \index{memory} memory space in bytes.}\\

\parhead{{\tt MEMORY\_PIXSTACK} }{ {\tt 300000} }{ {\em integer} }

\parlist{ Maximum number of pixels that the pixel-stack can contain. Multiply by 16 to 32 to get

                                            equivalent \index{memory} memory space in bytes.}\\

\parhead{{\tt PARAMETERS\_NAME} }{ {\tt default.param} }{ {\em string} }

\parlist{ The name of the file containing the list of parameters that will be computed and put

                                            in the catalogue for each object.}\\

\parhead{{\tt PHOT\_APERTURES} }{ {\tt 5} }{ {\em floats}\ $(n \le 32)$ }

\parlist{ Aperture diameters in pixels (used by {\tt MAG\_APER}).}\\

\parhead{{\tt PHOT\_AUTOPARAMS} }{ {\tt 2.5,3.5} }{ {\em floats}\ $(n=2)$ }

\parlist{ {\tt MAG\_AUTO} controls: scaling parameter $k$ of the 1st order moment, and minimum $R_{min}$

                                                        (in units of {\tt A} and {\tt B}).}\\

\parhead{{\tt PHOT\_AUTOAPERS}  }{ {\tt 0.0,0.0} }{ {\em floats}\ $(n=2)$ }

\parlist{ {\tt MAG\_AUTO} minimum (circular) aperture diameters: estimation disk, and

                                                          measurement disk.}\\

\parhead{{\tt PHOT\_FLUXFRAC}  }{ {\tt 0.5} }{ {\em floats}\ $(n \le 32)$ }

\parlist{ Fraction of {\tt FLUX\_AUTO} defining each element of the {\tt FLUX\_RADIUS} vector.}\\

\parhead{{\tt PIXEL\_SCALE}     }{ {\tt 1.0} }{ {\em float} }

\parlist{ Pixel size in arcsec (for surface brightness parameters, \index{FWHM} FWHM and star/galaxy separation only).}\\

\parhead{{\tt SATUR\_LEVEL}     }{ {\tt 50000.0} }{ {\em float} }

\parlist{ Pixel value above which it is considered saturated.}\\

\parhead{{\tt SEEING\_FWHM}     }{ {\tt 1.2} }{ {\em float} }

\parlist{ \index{FWHM} FWHM of stellar \index{image} images in arcsec (only for star/galaxy separation).}\\

\parhead{{\tt STARNNW\_NAME}    }{ {\tt default.nnw} }{ {\em string} }

\parlist{ Name of the file containing the neural-network weights for star/galaxy separation.}\\

\parhead{{\tt THRESH\_TYPE}       }{ {\tt RELATIVE} }{ {\em keywords}\ $(n

  \le 2)$  }

\parlist{ Meaning of the {\tt DETECT\_THRESH} and

                                                                                 {\tt ANALYSIS\_THRESH} parameters:}\\

\pararg{                            \tt RELATIVE}            {scaling factor to the \index{background RMS} background RMS,}

\pararg{                            \tt ABSOLUTE}             {absolute level (in ADUs or in surface brightness).}

\parhead{{\tt VERBOSE\_TYPE}    }{ {\tt NORMAL} }{ {\tt keyword}      }

\parlist{ How much {\sc SExtractor} comments its operations:}\\

\pararg{                                     \tt QUIET}        {run silently,}

\pararg{                                     \tt NORMAL}       {display warnings and limited info concerning the work in progress,}

\pararg{                                     \tt EXTRA\_WARNINGS} {like {\tt NORMAL}, plus a few more warnings if necessary,}

\pararg{                                     \tt FULL}       {display a more complete information and the principal parameters of all the objects

                                               extracted.}

\parhead{{\tt WEIGHT\_GAIN}   }{  {\tt Y}  }{ {\em boolean} }

\parlist{ If true, \index{weight map} \index{weight maps} weight maps are considered as \index{gain map} \index{gain maps} \index{gain} gain maps.}\\

\parhead{{\tt WEIGHT\_IMAGE}    }{ {\tt weight.fits} }{ {\em strings}\ $(n

  \le 2)$ }

\parlist{ File name of the detection and measurement ``weight-image'', respectively.}\\

\parhead{{\tt WEIGHT\_TYPE} }{ {\tt NONE} }{ {\em keywords} $(n \le 2)$ }

\parlist{ Weighting scheme (for single \index{image} image, or detection and

                                               measurement \index{image} images):}\\

\pararg{                                   \tt NONE}  {no weighting,}

\pararg{                                   \tt BACKGROUND} {variance map derived from the \index{image} image itself,}

\pararg{                                   \tt MAP\_RMS} {variance map derived from an external RMS map,}

\pararg{                                   \tt MAP\_VAR} {external \index{variance map} variance map,}

\pararg{                                   \tt MAP\_WEIGHT} {variance map derived from an external \index{weight map} weight map,}

\parhead{{\tt WRITE\_XML}       }{  {\tt N}  }{ {\em boolean} }

\parlist{ If true, meta-data will be written in \index{XML} XML-VOTable format.}\\

\parhead{{\tt \index{XML} XML\_NAME}        }{ {\tt sex.xml} }{ {\em string} }

\parlist{ File name for the \index{XML} XML output of {\sc SExtractor}.}\\

\end{tabbing}

\gam{I still need to check if parameters are missing with {\tt sex -dd}.}

\footnotetext[1]{Optional parameter}