Table Of Contents

Previous topic

The vmmosstandard recipe

Next topic

The vmspphot recipe

This Page

The vmspcaldisp recipe

vmspcaldisp

Synopsis

Determine spectral distortion models from flat field and arc lamp exposure.

Description

This recipe is used to determine all the spectral distortions and transformations from an arc lamp exposure and a master flat field produced by the recipe vmspflat.

Input files

DO category:               Type:       Explanation:         Required:
MOS_ARC_SPECTRUM           Raw         Arc lamp exposure       Y
MASTER_BIAS                Calib       Master bias             Y
MASTER_DARK                Calib       Master dark             .

MOS_MASTER_SCREEN_FLAT     Calib       Normalised flat field   .

MOS_COMBINED_SCREEN_FLAT   Calib       Combined flat field     .

GRISM_TABLE                Calib       Grism table             Y
LINE_CATALOG               Calib       Line catalog            Y
EXTRACT_TABLE              Calib       Extraction table        .

CCD_TABLE                  Calib       Bad pixel table         .

Output files

DO category:               Data type:  Explanation:
EXTRACT_TABLE              FITS table  Extraction table
MOS_ARC_SPECTRUM_EXTRACTED FITS image  Sky subtracted slit spectra
(none)                     PAF         Distortion models

At least one raw arc lamp exposure should be present in the input SOF.

The normalised and the combined flat fields are the products of the recipe vmspflat run on flat field data obtained with the same mask.

Neither of them is required for running vmspcaldisp, but if a combined flat field is not given then no spectral curvature model can be computed, and a first-guess is used in its place. A normalised master flat field needs to be specified only if a flat field correction is requested.

The bad pixel table needs to be specified only if the cleaning of bad pixels is requested.

An extraction table generated from previous runs might be input to the recipe, in order to iterate the modeling of the spectral distortions.

The grism table contains necessary information to control the way spectra are extracted and the determination of the distortion models.

The vmspcaldisp recipe gets from the grism table the wavelength that should be used as reference (header entry PRO WLEN CEN), and the spectrum extension in CCD pixels above and below the position of the reference wavelength (header entries PRO SPECT LLEN LO and PRO SPECT LLEN HI). Other parameters, used in the construction of the extracted arc lamp slit spectra, are the start and the end wavelength of the image containing the extracted spectra (header entries PRO WLEN START and PRO WLEN END), and the step of the sampling along the dispersion direction (header entry PRO WLEN INC).

The primary recipe product is the extraction table, that contains information about the local modelling of spectral distortions.

A secondary product of the vmspcaldisp recipe is the image of extracted slit spectra, that allows a visual check of the distortion models quality. A last product is the PAF file carrying all the information related to the spectral distortions. This PAF file is copied (or moved) to the product directory, and it is identical to the IWS configuration file MOS_wavecal_G_Q.cmf where Q indicates the VIMOS quadrant number, and G the grism name) that is created in the directory where vmspcaldisp is launched.

Constructor

cpl.Recipe("vmspcaldisp")

Create an object for the recipe vmspcaldisp.

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

Parameters

vmspcaldisp.param.BiasMethod

Bias removal method. (str; default: ‘Zmaster’) [default=”Zmaster”].

vmspcaldisp.param.Fuzz

Extra pixels from expected position of spectrum edge in spectral extraction. (long; default: 10) [default=10].

vmspcaldisp.param.RefineIDS

Refine Inverse Dispersion Solution. (bool; default: False) [default=False].

vmspcaldisp.param.ExtractionWindow

Size of search window around expected arc line positions. (long; default: 10) [default=10].

vmspcaldisp.param.ApplyFlatField

Flat field correction for input arc lamp frames. (bool; default: False) [default=False].

vmspcaldisp.param.CleanBadPixel

Bad pixel correction on arc lamp image. (bool; default: False) [default=False].

vmspcaldisp.param.CleanCosmic

Cosmic ray events cleaning in arc lamp image. (bool; default: False) [default=False].

vmspcaldisp.param.LineIdent

Arc line identification method. (str; default: ‘FirstGuess’) [default=”FirstGuess”].

vmspcaldisp.param.LineIdentLevel

Threshold for peak detection. (float; default: 500.0) [default=500.0].

vmspcaldisp.param.ArcExtraction

Arc lamp 2D extraction according to computed Local or Global IDS. (str; default: ‘Local’) [default=”Local”].

vmspcaldisp.param.ModelSlit

Model wavelength solution within each slit. (bool; default: True) [default=True].

vmspcaldisp.param.ModelSlitOrder

Order of polynomial for wavelength solution modeling within each slit. (long; default: 0) [default=0].

vmspcaldisp.param.ComputeQC

Compute QC1 parameters. (bool; default: True) [default=True].

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

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

vmspcaldisp.param.BiasMethod = "Zmaster"
vmspcaldisp.param.Fuzz = 10
vmspcaldisp.param.RefineIDS = False
vmspcaldisp.param.ExtractionWindow = 10
vmspcaldisp.param.ApplyFlatField = False
vmspcaldisp.param.CleanBadPixel = False
vmspcaldisp.param.CleanCosmic = False
vmspcaldisp.param.LineIdent = "FirstGuess"
vmspcaldisp.param.LineIdentLevel = 500.0
vmspcaldisp.param.ArcExtraction = "Local"
vmspcaldisp.param.ModelSlit = True
vmspcaldisp.param.ModelSlitOrder = 0
vmspcaldisp.param.ComputeQC = True

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

import cpl
vmspcaldisp = cpl.Recipe("vmspcaldisp")
[...]
res = vmspcaldisp( ..., param = {"BiasMethod":"Zmaster", "Fuzz":10})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to ESO VIMOS Pipeline Team and VIMOS Consortium. Alternatively, you may send a report to the ESO User Support Department.