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NAME

       fors_trace_flat - Determine spectral curvature model

SYNOPSIS

       esorex fors_trace_flat [OPTIONS] FILE.sof

DESCRIPTION

       This  recipe  is  used  to  trace the edges of MOS/MXU flat field slit spectra and determine the spectral
       curvature solution. The input master flat field image, product of the recipe fors_flat, is expected to be
       oriented with horizontal dispersion direction and red wavelengths on the right side.

       The input slits location table should be the product of the recipe fors_detect_spectra.

       The  input  master  flat  image  is shifted one pixel down and is subtracted from the original image. The
       result is a vertical gradient map. Next, the negative values are forced positive, to obtain  an  absolute
       gradient  map.  The  map is passed with a horizontal median filter, and after that the gradient peaks are
       traced starting from the slits positions listed in the input slits location table. The number  of  pixels
       to  the  left  and  to  the right of the reference pixel is trivially derived from the specified spectral
       range and spectral dispersion.

       The output spectral curvature table contains the coefficients of the  polynomial  fitting  of  the  found
       traces,  while the output trace table contains the traced spectral edges positions in CCD (Y) coordinates
       for each spectrum, and their comparison with their modeling. A spatial map is also created, where to each
       CCD  pixel  is  assigned  the value of the spatial coordinate along the slit (in pixel). For more details
       please refer to the FORS Pipeline UserĀ“s Manual.

       Note that specifying an input GRISM_TABLE will set some of the recipe configuration parameters to default
       values valid for a particular grism.

       Again, see the pipeline manual for more details.

       In the table below the MXU acronym can be alternatively read as MOS.

       Input files:

         DO category:               Type:       Explanation:         Required:
         MASTER_SCREEN_FLAT_MXU     Calib       Master flat frame       Y
         SLIT_LOCATION_DETECT_MXU   Calib       Slits location          Y
         GRISM_TABLE                Calib       Grism table             .

       Output files:

         DO category:               Data type:  Explanation:
         CURV_TRACES_MXU            FITS table  Flat field tracings
         CURV_COEFF_MXU             FITS table  Spectral curvature table
         SPATIAL_MAP_MXU            FITS image  Map of spatial coordinate

OPTIONS

       --dispersion <float>
              Expected  spectral dispersion (Angstrom/pixel) (float; default: 0.0). The full name of this option
              for the EsoRex configuration file is fors.fors_trace_flat.dispersion [default = 0.0].

       --startwavelength <float>
              Start wavelength in spectral extraction (float; default: 0.0). The full name of  this  option  for
              the EsoRex configuration file is fors.fors_trace_flat.startwavelength [default = 0.0].

       --endwavelength <float>
              End  wavelength in spectral extraction (float; default: 0.0). The full name of this option for the
              EsoRex configuration file is fors.fors_trace_flat.endwavelength [default = 0.0].

       --cdegree <int>
              Degree of spectral curvature polynomial (int; default: 0). The full name of this  option  for  the
              EsoRex configuration file is fors.fors_trace_flat.cdegree [default = 0].

       --cmode <int>
              Interpolation  mode  of  curvature solution applicable to MOS-like data (0 = no interpolation, 1 =
              fill gaps, 2 = global model) (int; default: 1). The full  name  of  this  option  for  the  EsoRex
              configuration file is fors.fors_trace_flat.cmode [default = 1].

       Note  that  it  is  possible to create a configuration file containing these options, along with suitable
       default values. Please refer to the details provided by the 'esorex --help' command.

SEE ALSO

       The full documentation for the fors pipeline can be downloaded as a PDF file using the following URL:

              ftp://ftp.eso.org/pub/dfs/pipelines/fors/fors-pipeline-manual-4.9.pdf

       An   overview   over   the   existing   ESO   pipelines    can    be    found    on    the    web    page
       https://www.eso.org/sci/software/pipelines/.

       Basic documentation about the EsoRex program can be found at the esorex (1) man page.

       It   is   possible   to   call   the   pipelines   from   python   using  the  python-cpl  package.   See
       https://packages.python.org/python-cpl/index.html for further information.

       The other recipes of  the  fors  pipeline  are  fors_align_sky(7),  fors_align_sky_lss(7),  fors_bias(7),
       fors_calib(7),     fors_config(7),    fors_dark(7),    fors_detect_objects(7),    fors_detect_spectra(7),
       fors_extract(7), fors_extract_objects(7), fors_extract_slits(7), fors_flatfield(7),  fors_img_science(7),
       fors_img_screen_flat(7),      fors_img_sky_flat(7),      fors_normalise_flat(7),      fors_photometry(7),
       fors_pmos_calib(7), fors_pmos_extract(7),  fors_pmos_science(7),  fors_remove_bias(7),  fors_resample(7),
       fors_science(7),  fors_spec_mflat(7),  fors_subtract_sky(7),  fors_subtract_sky_lss(7),  fors_sumflux(7),
       fors_wave_calib(7), fors_wave_calib_lss(7), fors_zeropoint(7)

VERSION

       fors_trace_flat 5.5.7

AUTHOR

       Carlo Izzo <usd-help@eso.org>

BUG REPORTS

       Please report any problems to usd-help@eso.org. Alternatively, you may send a  report  to  the  ESO  User
       Support Department <usd-help@eso.org>.

LICENSE

       This  file  is  currently  part of the FORS Instrument Pipeline Copyright (C) 2002-2010 European Southern
       Observatory

       This program is free software; you can redistribute it and/or modify  it  under  the  terms  of  the  GNU
       General  Public License as published by the Free Software Foundation; either version 2 of the License, or
       (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY  WARRANTY;  without  even
       the  implied  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
       License for more details.

       You should have received a copy of the GNU General Public License along with this program; if not,  write
       to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA