The vmmosstandard recipe¶
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vmmosstandard
¶
Synopsis¶
Reduce a MOS standard star exposure.
Description¶
This recipe is used to calibrate and extract a standard star spectrum obtained in MOS mode, and compare it with a catalog spectrum to obtain the efficiency and the response curves.
Input files¶
DO category: Type: Explanation: Required:
MOS_STANDARD Raw Science exposure Y
MASTER_BIAS Calib Master bias Y
EXTINCT_TABLE Calib Atmospheric extinction Y
STD_FLUX_TABLE Calib Standard star fluxes Y
MASTER_DARK Calib Master dark .
MOS_MASTER_SCREEN_FLAT Calib Normalised flat field .
EXTRACT_TABLE Calib Extraction table .
GRISM_TABLE Calib Grism table Y
CCD_TABLE Calib Bad pixel table .
Output files¶
DO category: Data type: Explanation:
MOS_STANDARD_REDUCED FITS image Extracted spectrum
MOS_STANDARD_EXTRACTED FITS image Sky subtracted slit spectra
MOS_STANDARD_SKY FITS image Sky slit spectra
MOS_STANDARD_SKY_EXTRACTED FITS image Extracted sky spectrum
OBJECT_TABLE FITS table Objects spectra identification
WINDOW_TABLE FITS table Objects positions in slit
MOS_SPECPHOT_TABLE FITS table Efficiency and response curves
The standard star spectrum is calibrated and extracted as described for the recipe vmmosobsstare. The extracted spectrum is compared to catalog fluxes of the same star to obtain the efficiency curve and the response curve to use for flux calibration. For this comparison the extracted spectrum is converted into electrons/sec/Angstrom. The catalog fluxes, as well as the atmospheric extinction factors, are remapped to the same wavelength bins of the extracted spectrum. After removing the effect of the atmospheric extinction (i.e., correcting the extracted spectrum to airmass zero), the response curve is derived as the ratio between the catalog spectrum and the calibrated spectrum.
The efficiency curve is obtained by dividing the extracted spectrum in electrons/sec/Angstrom by the the catalog fluxes converted from erg/cm/cm/s/Angstrom to photons/s/Angstrom (at 100% efficiency each photon would correspond to one electron).
For more details, please refer to the VIMOS Pipeline User’s Guide.
Constructor¶
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cpl.
Recipe
("vmmosstandard") Create an object for the recipe vmmosstandard.
import cpl
vmmosstandard = cpl.Recipe("vmmosstandard")
Parameters¶
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vmmosstandard.param.
BiasMethod
¶ Bias removal method. (str; default: ‘Zmaster’) [default=”Zmaster”].
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vmmosstandard.param.
SkyMethod
¶ Sky level determination method. (str; default: ‘Median’) [default=”Median”].
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vmmosstandard.param.
PolyOrder
¶ Degree of polynomial used when the SkyMethod is set to Fit. (int; default: 0) [default=0].
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vmmosstandard.param.
SkyKSigmaLow
¶ Low threshold for K-sigma rejection in sky fitting. (float; default: 3.0) [default=3.0].
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vmmosstandard.param.
SkyKSigmaHigh
¶ High threshold for K-sigma rejection in sky fitting. (float; default: 3.0) [default=3.0].
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vmmosstandard.param.
Fuzz
¶ Extra pixels from expected position of spectrum edge in extraction. (int; default: 5) [default=5].
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vmmosstandard.param.
SlitMargin
¶ Number of excluded pixels at slit ends in object search or in sky level determination. (int; default: 2) [default=2].
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vmmosstandard.param.
LineWidth
¶ Size of spectrum to extract around any skyline. (int; default: 16) [default=16].
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vmmosstandard.param.
DetectionLevel
¶ Object detection level in units of sigma. (float; default: 10.0) [default=10.0].
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vmmosstandard.param.
WatershedLevels
¶ Number of levels in the watershed method in object detection. (int; default: 32) [default=32].
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vmmosstandard.param.
WatershedFraction
¶ Flux fraction to use in watershed. (float; default: 0.01) [default=0.01].
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vmmosstandard.param.
MinObjectSize
¶ Minimal size for an object candidate to be considered an object. (int; default: 2) [default=2].
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vmmosstandard.param.
MaxObjectSize
¶ Maximal size for an object candidate for not trying deblend into sub- objects. (int; default: 7) [default=7].
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vmmosstandard.param.
CleanBadPixel
¶ Bad pixel correction on MOS science exposure. (bool; default: True) [default=True].
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vmmosstandard.param.
HorneExtraction
¶ Use 1D Horne extraction. (bool; default: False) [default=False].
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vmmosstandard.param.
ModelSlit
¶ Model wavelength solution within each slit. (bool; default: True) [default=True].
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vmmosstandard.param.
ModelSlitOrder
¶ Order of polynomial for wavelength solution modeling within each slit. (int; default: 0) [default=0].
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vmmosstandard.param.
UseSkylines
¶ Use sky lines to refine the wavelength calibration (bool; default: True) [default=True].
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vmmosstandard.param.
ResponseOrder
¶ Order of the polynomial used to smooth the instrument response curve. (int; default: 5) [default=5].
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vmmosstandard.param.
ReduceAnyFrame
¶ Reduce any frame. (bool; default: False) [default=False].
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vmmosstandard.param.
ComputeQC
¶ Compute QC1 parameters (bool; default: True) [default=True].
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vmmosstandard.param.
SelectSlit
¶ Slit containing the standard star. (int; default: 0) [default=0].
The following code snippet shows the default settings for the available parameters.
import cpl
vmmosstandard = cpl.Recipe("vmmosstandard")
vmmosstandard.param.BiasMethod = "Zmaster"
vmmosstandard.param.SkyMethod = "Median"
vmmosstandard.param.PolyOrder = 0
vmmosstandard.param.SkyKSigmaLow = 3.0
vmmosstandard.param.SkyKSigmaHigh = 3.0
vmmosstandard.param.Fuzz = 5
vmmosstandard.param.SlitMargin = 2
vmmosstandard.param.LineWidth = 16
vmmosstandard.param.DetectionLevel = 10.0
vmmosstandard.param.WatershedLevels = 32
vmmosstandard.param.WatershedFraction = 0.01
vmmosstandard.param.MinObjectSize = 2
vmmosstandard.param.MaxObjectSize = 7
vmmosstandard.param.CleanBadPixel = True
vmmosstandard.param.HorneExtraction = False
vmmosstandard.param.ModelSlit = True
vmmosstandard.param.ModelSlitOrder = 0
vmmosstandard.param.UseSkylines = True
vmmosstandard.param.ResponseOrder = 5
vmmosstandard.param.ReduceAnyFrame = False
vmmosstandard.param.ComputeQC = True
vmmosstandard.param.SelectSlit = 0
You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:
import cpl
vmmosstandard = cpl.Recipe("vmmosstandard")
[...]
res = vmmosstandard( ..., param = {"BiasMethod":"Zmaster", "SkyMethod":"Median"})
See also
cpl.Recipe for more information about the recipe object.
Bug reports¶
Please report any problems to ESO VIMOS Pipeline Team. Alternatively, you may send a report to the ESO User Support Department.
Copyright¶
This file is part of the VIMOS Instrument Pipeline Copyright (C) 2002-2005 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: ESO VIMOS Pipeline Team <usd-help@eso.org>