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       fors_subtract_sky - Subtract sky from scientific spectra


       esorex fors_subtract_sky [OPTIONS] FILE.sof


       This  recipe  is  used  to subtract the sky emission from unrebinned slit spectra. This is
       obtained by robust fitting (i.e., excluding the signal from possible point-like objects in
       slit)  of  the  emission  along the CCD columns within each spectrum). This method doesn´t
       work if extended objects are in slit (it really destroys the object spectra), and  is  not
       applicable  to  LSS  data.  The  input  scientific  frames  are  produced  by  the recipes
       fors_remove_bias and fors_flatfield.

       This recipe cannot be applied to LSS or long-slit like data (MOS/MXU with all slits at the
       same offset). No automatic recipe is available for this.

       Please refer to the FORS Pipeline User´s Manual for more details.

       In the table below the MXU acronym can be alternatively read as MOS, and SCI as STD.

       Input files:

         DO category:               Type:       Explanation:         Required:
         or STANDARD_UNFLAT_MXU     Calib       Frame with sky lines    Y
         CURV_COEFF_MXU             Calib       Spectral curvature      Y
         SLIT_LOCATION_MXU          Calib       Slit location on CCD    Y
         GRISM_TABLE                Calib       Grism table             .

       Output files:

         DO category:               Data type:  Explanation:
         or UNMAPPED_STD_MXU        FITS image  Sky subtracted scientific frame
         or UNMAPPED_SKY_STD_MXU    FITS image  Subtracted sky frame


       --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_subtract_sky.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_subtract_sky.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_subtract_sky.endwavelength
              [default = 0.0].

       --cosmics <bool>
              Eliminate cosmic rays hits (bool; default: False). The full name of this option for
              the EsoRex configuration file is fors.fors_subtract_sky.cosmics [default = False].

       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'


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


       An   overview   over   the   existing   ESO  pipelines  can  be  found  on  the  web  page

       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 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_lss(7),    fors_sumflux(7),   fors_trace_flat(7),
       fors_wave_calib(7), fors_wave_calib_lss(7), fors_zeropoint(7)


       fors_subtract_sky 5.3.32


       Carlo Izzo <>


       Please report any problems to Alternatively, you may send  a  report  to
       the ESO User Support Department <>.


       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