The fors_wave_calib_lss recipe

fors_wave_calib_lss

Synopsis

Derive dispersion relation from long-slit arc lamp frame

Description

This recipe is used to wavelength calibrate one long slit spectrum, i.e., a FORS spectral obtained either in LSS mode or in MOS/MXU mode with all slits at the same offset. A pattern-matching algorithm is applied as in recipe fors_detect_spectra. For more details on this data reduction strategy please refer to the FORS Pipeline User’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.

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

Input files

DO category:               Type:       Explanation:         Required:
LAMP_UNBIAS_LSS            Calib       Arc lamp exposure       Y
MASTER_LINECAT             Calib       Line catalog            Y
GRISM_TABLE                Calib       Grism table             .

Output files

DO category:               Data type:  Explanation:
REDUCED_LAMP_LSS           FITS image  Calibrated arc lamp exposure
DISP_COEFF_LSS             FITS table  Inverse dispersion coefficients
DISP_RESIDUALS_LSS         FITS image  Image of modeling residuals
WAVELENGTH_MAP_LSS         FITS image  Wavelengths mapped on CCD
SLIT_LOCATION_LSS          FITS image  Background subtracted arc frame
SPECTRAL_RESOLUTION_LSS    FITS table  Spectral resolution table

Constructor

cpl.Recipe("fors_wave_calib_lss")

Create an object for the recipe fors_wave_calib_lss.

import cpl
fors_wave_calib_lss = cpl.Recipe("fors_wave_calib_lss")

Parameters

fors_wave_calib_lss.param.dispersion

Expected spectral dispersion (Angstrom/pixel) (float; default: 0.0) [default=0.0].

fors_wave_calib_lss.param.peakdetection

Initial peak detection threshold (ADU) (float; default: 0.0) [default=0.0].

fors_wave_calib_lss.param.wdegree

Degree of wavelength calibration polynomial (int; default: 0) [default=0].

fors_wave_calib_lss.param.wradius

Search radius if iterating pattern-matching with first-guess method (int; default: 4) [default=4].

fors_wave_calib_lss.param.wreject

Rejection threshold in dispersion relation fit (pixel) (float; default: 0.7) [default=0.7].

fors_wave_calib_lss.param.wcolumn

Name of line catalog table column with wavelengths (str; default: ‘WLEN’) [default=”WLEN”].

fors_wave_calib_lss.param.startwavelength

Start wavelength in spectral extraction (float; default: 0.0) [default=0.0].

fors_wave_calib_lss.param.endwavelength

End wavelength in spectral extraction (float; default: 0.0) [default=0.0].

fors_wave_calib_lss.param.wmode

Interpolation mode of wavelength solution (0 = no interpolation, 1 = fill gaps, 2 = global model) (int; default: 2) [default=2].

The following code snippet shows the default settings for the available parameters.

import cpl
fors_wave_calib_lss = cpl.Recipe("fors_wave_calib_lss")

fors_wave_calib_lss.param.dispersion = 0.0
fors_wave_calib_lss.param.peakdetection = 0.0
fors_wave_calib_lss.param.wdegree = 0
fors_wave_calib_lss.param.wradius = 4
fors_wave_calib_lss.param.wreject = 0.7
fors_wave_calib_lss.param.wcolumn = "WLEN"
fors_wave_calib_lss.param.startwavelength = 0.0
fors_wave_calib_lss.param.endwavelength = 0.0
fors_wave_calib_lss.param.wmode = 2

You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:

import cpl
fors_wave_calib_lss = cpl.Recipe("fors_wave_calib_lss")
[...]
res = fors_wave_calib_lss( ..., param = {"dispersion":0.0, "peakdetection":0.0})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

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