Upgrade wavelength solution using sky lines
This recipe is used to align the wavelength solution based on the arc lamp exposure on a set of sky lines observed on a scientific exposure.
The input rectified frames are produced by the recipe fors_extract_slits.
An input catalog of sky lines can be specified, otherwise an internal one is used.
This recipe should be applied to multi-slit MOS/MXU data: for LSS or long-slit like data (MOS/MXU with all slits at the same offset) use recipe fors_align_sky_lss instead. 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.
DO category: Type: Explanation: Required:
RECTIFIED_ALL_SCI_MXU
or RECTIFIED_SKY_SCI_MXU Calib Frame with sky lines Y
SPATIAL_MAP_MXU Calib Spatial coordinate map Y
CURV_COEFF_MXU Calib Spectral curvature Y
SLIT_LOCATION_MXU Calib Slit location on CCD Y
DISP_COEFF_MXU Calib Dispersion solution Y
MASTER_SKYLINECAT Calib Catalog of sky lines .
GRISM_TABLE Calib Grism table .
DO category: Data type: Explanation:
SKY_SHIFTS_SLIT_SCI_MXU FITS table Observed sky lines offsets
WAVELENGTH_MAP_SCI_MXU FITS image Wavelength mapped on CCD
DISP_COEFF_SCI_MXU FITS image Upgraded dispersion solution
Create an object for the recipe fors_align_sky.
import cpl
fors_align_sky = cpl.Recipe("fors_align_sky")
Expected spectral dispersion (Angstrom/pixel) (float; default: 0.0) [default=0.0].
Start wavelength in spectral extraction (float; default: 0.0) [default=0.0].
End wavelength in spectral extraction (float; default: 0.0) [default=0.0].
Polynomial order for sky lines alignment (long; default: 0) [default=0].
Name of sky line catalog table column with wavelengths (str; default: ‘WLEN’) [default=”WLEN”].
The following code snippet shows the default settings for the available parameters.
import cpl
fors_align_sky = cpl.Recipe("fors_align_sky")
fors_align_sky.param.dispersion = 0.0
fors_align_sky.param.startwavelength = 0.0
fors_align_sky.param.endwavelength = 0.0
fors_align_sky.param.skyalign = 0
fors_align_sky.param.wcolumn = "WLEN"
You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:
import cpl
fors_align_sky = cpl.Recipe("fors_align_sky")
[...]
res = fors_align_sky( ..., param = {"dispersion":0.0, "startwavelength":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>