Determination of the extraction mask
This recipe is used to identify reference lines on PMOS arc lamp exposures, and trace the spectral edges on the corresponding flat field exposures. This information is used to determine the spectral extraction mask to be applied in the scientific data reduction, performed with the recipe fors_science.
This recipe accepts both FORS1 and FORS2 frames. The input arc lamps and flat field exposures are assumed to be obtained quasi-simultaneously, so that they would be described by exactly the same instrument distortions.
A line catalog must be specified, containing the wavelengths of the reference arc lamp lines used for the wavelength calibration. 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). Finally a master bias frame must be input to this recipe.
The products SPECTRA_DETECTION_PMOS, SLIT_MAP_PMOS, and DISP_RESIDUALS_PMOS, are just created if the –check parameter is set to true.
The MASTER_DISTORTION_TABLE is marked as required, but it is not so if all slits have different offsets, and in the case of FORS1 observations made with the old TK2048EB4-1 1604 chip read in windowed mode (2048x400)
DO category: Type: Explanation: Required:
SCREEN_FLAT_PMOS Raw Flat field exposures Y
LAMP_PMOS Raw Arc lamp exposure Y
MASTER_BIAS or BIAS Calib Bias frame Y
MASTER_LINECAT Calib Line catalog Y
GRISM_TABLE Calib Grism table .
MASTER_DISTORTION_TABLE Calib Master distortions table Y
DO category: Data type: Explanation:
MASTER_SCREEN_FLAT_PMOS FITS image Combined (sum) flat field
MASTER_NORM_FLAT_PMOS FITS image Normalised flat field
MAPPED_SCREEN_FLAT_PMOS FITS image Wavelength calibrated flat field
MAPPED_NORM_FLAT_PMOS FITS image Wavelength calibrated normalised flat
REDUCED_LAMP_PMOS FITS image Wavelength calibrated arc spectrum
DISP_COEFF_PMOS FITS table Inverse dispersion coefficients
DISP_RESIDUALS_PMOS FITS image Residuals in wavelength calibration
DISP_RESIDUALS_TABLE_PMOS FITS table Residuals in wavelength calibration
DELTA_IMAGE_PMOS FITS image Offset vs linear wavelength calib
WAVELENGTH_MAP_PMOS FITS image Wavelength for each pixel on CCD
SPECTRA_DETECTION_PMOS FITS image Check for preliminary detection
SLIT_MAP_PMOS FITS image Map of central wavelength on CCD
CURV_TRACES_PMOS FITS table Spectral curvature traces
CURV_COEFF_PMOS FITS table Spectral curvature coefficients
SPATIAL_MAP_PMOS FITS image Spatial position along slit on CCD
SPECTRAL_RESOLUTION_PMOS FITS table Resolution at reference arc lines
SLIT_LOCATION_PMOS FITS table Slits on product frames and CCD
Create an object for the recipe fors_pmos_calib.
import cpl
fors_pmos_calib = cpl.Recipe("fors_pmos_calib")
Expected spectral dispersion (Angstrom/pixel) (float; default: 0.0) [default=0.0].
Initial peak detection threshold (ADU) (float; default: 0.0) [default=0.0].
Degree of wavelength calibration polynomial (long; default: 0) [default=0].
Search radius if iterating pattern-matching with first-guess method (long; default: 4) [default=4].
Rejection threshold in dispersion relation fit (pixel) (float; default: 0.7) [default=0.7].
Name of line catalog table column with wavelengths (str; default: ‘WLEN’) [default=”WLEN”].
Degree of spectral curvature polynomial (long; default: 0) [default=0].
Interpolation mode of curvature solution (0 = no interpolation, 1 = fill gaps, 2 = global model) (long; default: 1) [default=1].
Start wavelength in spectral extraction (float; default: 0.0) [default=0.0].
End wavelength in spectral extraction (float; default: 0.0) [default=0.0].
Frames combination method (str; default: ‘average’) [default=”average”].
Number of lowest values to be rejected (long; default: 1) [default=1].
Number of highest values to be rejected (long; default: 1) [default=1].
Low threshold in ksigma method (float; default: 3.0) [default=3.0].
High threshold in ksigma method (float; default: 3.0) [default=3.0].
Max number of iterations in ksigma method (long; default: 999) [default=999].
Degree of flat field fitting polynomial along dispersion direction (long; default: -1) [default=-1].
Smooth box radius for flat field along dispersion direction (long; default: 10) [default=10].
Compute QC1 parameters (bool; default: True) [default=True].
Create intermediate products (bool; default: False) [default=False].
The following code snippet shows the default settings for the available parameters.
import cpl
fors_pmos_calib = cpl.Recipe("fors_pmos_calib")
fors_pmos_calib.param.dispersion = 0.0
fors_pmos_calib.param.peakdetection = 0.0
fors_pmos_calib.param.wdegree = 0
fors_pmos_calib.param.wradius = 4
fors_pmos_calib.param.wreject = 0.7
fors_pmos_calib.param.wcolumn = "WLEN"
fors_pmos_calib.param.cdegree = 0
fors_pmos_calib.param.cmode = 1
fors_pmos_calib.param.startwavelength = 0.0
fors_pmos_calib.param.endwavelength = 0.0
fors_pmos_calib.param.stack_method = "average"
fors_pmos_calib.param.minrejection = 1
fors_pmos_calib.param.maxrejection = 1
fors_pmos_calib.param.klow = 3.0
fors_pmos_calib.param.khigh = 3.0
fors_pmos_calib.param.kiter = 999
fors_pmos_calib.param.ddegree = -1
fors_pmos_calib.param.dradius = 10
fors_pmos_calib.param.qc = True
fors_pmos_calib.param.check = False
You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:
import cpl
fors_pmos_calib = cpl.Recipe("fors_pmos_calib")
[...]
res = fors_pmos_calib( ..., param = {"dispersion":0.0, "peakdetection":0.0})
See also
cpl.Recipe for more information about the recipe object.
Please report any problems to Carlo Izzo. 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
Code author: Carlo Izzo <usd-help@eso.org>