The fors_align_sky_lss recipe

fors_align_sky_lss

Synopsis

Upgrade wavelength solution using sky lines

Description

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 scientific frames are produced by the recipes fors_remove_bias and fors_flatfield. An input catalog of sky lines can be specified, or an internal one is used.

This recipe should be applied to LSS or long-slit like data (MOS/MXU with all slits at the same offset). For multi-slit MOS/MXU data use recipe fors_align_sky 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 LSS, and SCI as STD.

Input files

DO category:               Type:       Explanation:         Required:
SCIENCE_UNBIAS_MXU
or SCIENCE_UNFLAT_MXU
or STANDARD_UNBIAS_MXU
or STANDARD_UNFLAT_MXU     Calib       Frame with sky lines    Y
DISP_COEFF_MXU             Calib       Dispersion solution     Y
SLIT_LOCATION_MXU          Calib       Slit location on CCD    Y
MASTER_SKYLINECAT          Calib       Catalog of sky lines    .

GRISM_TABLE                Calib       Grism table             .

Output files

DO category:               Data type:  Explanation:
SKY_SHIFTS_LONG_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

Constructor

cpl.Recipe("fors_align_sky_lss")

Create an object for the recipe fors_align_sky_lss.

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

Parameters

fors_align_sky_lss.param.dispersion

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

fors_align_sky_lss.param.startwavelength

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

fors_align_sky_lss.param.endwavelength

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

fors_align_sky_lss.param.skyalign

Polynomial order for sky lines alignment (int; default: 0) [default=0].

fors_align_sky_lss.param.wcolumn

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_lss = cpl.Recipe("fors_align_sky_lss")

fors_align_sky_lss.param.dispersion = 0.0
fors_align_sky_lss.param.startwavelength = 0.0
fors_align_sky_lss.param.endwavelength = 0.0
fors_align_sky_lss.param.skyalign = 0
fors_align_sky_lss.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_lss = cpl.Recipe("fors_align_sky_lss")
[...]
res = fors_align_sky_lss( ..., param = {"dispersion":0.0, "startwavelength":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.