Determination of the extraction mask
This recipe is used to identify reference lines on MOS 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 vimos_science. The input arc lamp 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.
In the table below the MOS_CURV_COEFF, MOS_CURV_TRACES, MOS_SPATIAL_MAP MOS_ARC_SPECTRUM_EXTRACTED, MOS_SPECTRA_DETECTION, MOS_SLIT_MAP, and MOS_SLIT_LOCATION, are never created in case of long-slit-like data.
The products MOS_SPECTRA_DETECTION, MOS_SLIT_MAP, and MOS_DISP_RESIDUALS, are just created if the –check parameter is set to true. The product GLOBAL_DISTORTION_TABLE is just created if more than 12 separate spectra are found in the CCD.
DO category: Type: Explanation: Required:
MOS_SCREEN_FLAT Raw Flat field exposures Y
MOS_ARC_SPECTRUM Raw Arc lamp exposure Y
MASTER_BIAS or BIAS Calib Bias frame Y
LINE_CATALOG Calib Line catalog Y
CONFIG_TABLE Calib Grism table .
DO category: Data type: Explanation:
MOS_COMBINED_SCREEN_FLAT FITS image Combined (sum) flat field
MOS_MASTER_SCREEN_FLAT FITS image Normalised flat field
MOS_ARC_SPECTRUM_EXTRACTED FITS image Wavelength calibrated arc spectrum
MOS_DISP_COEFF FITS table Inverse dispersion coefficients
MOS_DISP_RESIDUALS FITS image Residuals in wavelength calibration
MOS_DISP_RESIDUALS_TABLE FITS table Residuals in wavelength calibration
MOS_DELTA_IMAGE FITS image Offset vs linear wavelength calib
MOS_WAVELENGTH_MAP FITS image Wavelength for each pixel on CCD
MOS_SPECTRA_DETECTION FITS image Check for preliminary detection
MOS_SLIT_MAP FITS image Map of central wavelength on CCD
MOS_CURV_TRACES FITS table Spectral curvature traces
MOS_CURV_COEFF FITS table Spectral curvature coefficients
MOS_SPATIAL_MAP FITS image Spatial position along slit on CCD
MOS_SPECTRAL_RESOLUTION FITS table Resolution at reference arc lines
MOS_SLIT_LOCATION FITS table Slits on product frames and CCD
GLOBAL_DISTORTION_TABLE FITS table Global distortions table
Create an object for the recipe vmmoscalib.
import cpl
vmmoscalib = cpl.Recipe("vmmoscalib")
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 (pixel) (long; default: 4) [default=4].
Rejection threshold in dispersion relation fit (pixel) (float; default: 0.7) [default=0.7].
Interpolation mode of wavelength solution (0 = no interpolation, 1 = fill gaps, 2 = global model) (long; default: 2) [default=2].
Interpolation mode of wavelength solution (0 = no interpolation, 1 = local (slit) solution, 2 = global model) (long; default: 1) [default=1].
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 applicable to MOS-like data (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].
Reference wavelength for calibration (float; default: 0.0) [default=0.0].
Attempt slit identification (bool; default: True) [default=True].
Degree of flat field fitting polynomial along spatial direction (used for LSS-like data only) (long; default: -1) [default=-1].
Degree of flat field fitting polynomial along dispersion direction (not used for long-slit-like data) (long; default: -1) [default=-1].
Smooth box radius for flat field along dispersion direction (long; default: 10) [default=10].
Smooth box radius for flat field along spatial direction (long; default: 10) [default=10].
The following code snippet shows the default settings for the available parameters.
import cpl
vmmoscalib = cpl.Recipe("vmmoscalib")
vmmoscalib.param.dispersion = 0.0
vmmoscalib.param.peakdetection = 0.0
vmmoscalib.param.wdegree = 0
vmmoscalib.param.wradius = 4
vmmoscalib.param.wreject = 0.7
vmmoscalib.param.wmodelss = 2
vmmoscalib.param.wmodemos = 1
vmmoscalib.param.wcolumn = "WLEN"
vmmoscalib.param.cdegree = 0
vmmoscalib.param.cmode = 1
vmmoscalib.param.startwavelength = 0.0
vmmoscalib.param.endwavelength = 0.0
vmmoscalib.param.reference = 0.0
vmmoscalib.param.slit_ident = True
vmmoscalib.param.sdegree = -1
vmmoscalib.param.ddegree = -1
vmmoscalib.param.dradius = 10
vmmoscalib.param.sradius = 10
You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:
import cpl
vmmoscalib = cpl.Recipe("vmmoscalib")
[...]
res = vmmoscalib( ..., 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 VIMOS Instrument Pipeline Copyright (C) 2002-2006 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>