fors_extract7

Usage

Overview

This recipe is used to reduce scientific spectra using the global distortion table created by the recipe fors_calib. The spectra are bias subtracted, flat fielded (if a normalised flat field is specified) and remapped eliminating the optical distortions. The wavelength calibration can be optionally upgraded using a number of sky lines: if no sky lines catalog of wavelengths is specified, an internal one is used instead.

If the alignment to the sky lines is performed, the applied dispersion coefficient table is upgraded and saved to disk, and a new CCD wavelengths map is created.

This recipe accepts both FORS1 and FORS2 frames. A grism table (typically depending on the instrument mode, and in particular on the grism used) may also be specified: this table contains a default recipe parameter setting to control the way spectra are extracted for a specific instrument mode, as it is used for automatic run of the pipeline on Paranal and in Garching. If this table is specified, it will modify the default recipe parameter setting, with the exception of those parameters which have been explicitly modifyed on the command line. If a grism table is not specified, the input recipe parameters values will always be read from the command line, or from an esorex configuration file if present, or from their generic default values (that are rarely meaningful).

In the table below the MXU acronym can be read alternatively as MOS and LSS, depending on the instrument mode of the input data. Either a scientific or a standard star exposure can be specified in input (not both).

Input files:

DO category: Type: Explanation: Required:
SCIENCE_MXU Raw Scientific exposure Y
or STANDARD_MXU Raw Standard star exposure Y
MASTER_BIAS Calib Master bias Y
GRISM_TABLE Calib Grism table .

MASTER_SKYLINECAT Calib Sky lines catalog .

MASTER_NORM_FLAT_MXU Calib Normalised flat field .

MASTER_DISTORTION_TABLE Calib Global distortion model .

or, in case of LSS-like MOS/MXU data,

MASTER_NORM_FLAT_LONG_MXU Calib Normalised flat field .

Output files:

DO category: Data type: Explanation:
REDUCED_SCI_MXU FITS image Extracted scientific spectra
REDUCED_SKY_SCI_MXU FITS image Extracted sky spectra
REDUCED_ERROR_SCI_MXU FITS image Errors on extracted spectra
UNMAPPED_SCI_MXU FITS image Sky subtracted scientific spectra
MAPPED_SCI_MXU FITS image Rectified scientific spectra
MAPPED_ALL_SCI_MXU FITS image Rectified science spectra with sky
MAPPED_SKY_SCI_MXU FITS image Rectified sky spectra
UNMAPPED_SKY_SCI_MXU FITS image Sky on CCD
GLOBAL_SKY_SPECTRUM_MXU FITS table Global sky spectrum
OBJECT_TABLE_SCI_MXU FITS table Positions of detected objects

Only if the sky-alignment of the wavelength solution is requested:
SKY_SHIFTS_LONG_SCI_MXU FITS table Sky lines offsets (LSS-like data)
or SKY_SHIFTS_SLIT_SCI_MXU FITS table Sky lines offsets (MOS-like data)
DISP_COEFF_SCI_MXU FITS table Upgraded dispersion coefficients
WAVELENGTH_MAP_SCI_MXU FITS image Upgraded wavelength map

Options

--dispersion <float>

Resampling step (Angstrom/pixel) (float; default: 0.0). The full name of this option for the EsoRex configuration file is fors.fors_extract.dispersion [default = 0.0].

--skyalign <int>

Polynomial order for sky lines alignment, or -1 to avoid alignment (int; default: 0). The full name of this option for the EsoRex configuration file is fors.fors_extract.skyalign [default = 0].

--wcolumn <str>

Name of sky line catalog table column with wavelengths (str; default: ´WLEN´). The full name of this option for the EsoRex configuration file is fors.fors_extract.wcolumn [default = WLEN].

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

--flux <bool>

Apply flux conservation (bool; default: True). The full name of this option for the EsoRex configuration file is fors.fors_extract.flux [default = True].

--flatfield <bool>

Apply flat field (bool; default: False). The full name of this option for the EsoRex configuration file is fors.fors_extract.flatfield [default = False].

--skyglobal <bool>

Subtract global sky spectrum from CCD (bool; default: False). The full name of this option for the EsoRex configuration file is fors.fors_extract.skyglobal [default = False].

--skymedian <bool>

Sky subtraction from extracted slit spectra (bool; default: False). The full name of this option for the EsoRex configuration file is fors.fors_extract.skymedian [default = False].

--skylocal <bool>

Sky subtraction from CCD slit spectra (bool; default: True). The full name of this option for the EsoRex configuration file is fors.fors_extract.skylocal [default = True].

--cosmics <bool>

Eliminate cosmic rays hits (only if global sky subtraction is also requested) (bool; default: False). The full name of this option for the EsoRex configuration file is fors.fors_extract.cosmics [default = False].

--slit_margin <int>

Number of pixels to exclude at each slit in object detection and extraction (int; default: 3). The full name of this option for the EsoRex configuration file is fors.fors_extract.slit_margin [default = 3].

--ext_radius <int>

Maximum extraction radius for detected objects (pixel) (int; default: 6). The full name of this option for the EsoRex configuration file is fors.fors_extract.ext_radius [default = 6].

--cont_radius <int>

Minimum distance at which two objects of equal luminosity do not contaminate each other (pixel) (int; default: 0). The full name of this option for the EsoRex configuration file is fors.fors_extract.cont_radius [default = 0].

--ext_mode <int>

Object extraction method: 0 = aperture, 1 = Horne optimal extraction (int; default: 1). The full name of this option for the EsoRex configuration file is fors.fors_extract.ext_mode [default = 1].

--time_normalise <bool>

Normalise output spectra by the exposure time (bool; default: True). The full name of this option for the EsoRex configuration file is fors.fors_extract.time_normalise [default = True].

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.

Version

fors_extract 5.5.6