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The muse_astrometry recipe

muse_astrometry

Synopsis

Compute an astrometric solution.

Description

Merge pixel tables from all IFUs, apply correction for differential atmospheric refraction, optionally apply flux calibration and telluric correction (if the necessary input data was given), and resample the data from all exposures into a datacube. Use the cube to detect objects which are then matched to their reference positions from which a two-dimensional WCS solution is computed.

Constructor

cpl.Recipe("muse_astrometry")

Create an object for the recipe muse_astrometry.

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

Parameters

muse_astrometry.param.centroid

Centroiding method to use for objects in the field of view. “gaussian” and “moffat” use 2D fits to derive the centroid, “box” is a simple centroid in a square box. (str; default: ‘moffat’) [default=”moffat”].

muse_astrometry.param.detsigma

Source detection sigma level to use. (float; default: 3.0) [default=3.0].

muse_astrometry.param.radius

Initial radius in pixels for pattern matching identification in the astrometric field. (float; default: 5.0) [default=5.0].

muse_astrometry.param.faccuracy

Factor of initial accuracy relative to mean positional accuracy of the measured positions to use for pattern matching. (float; default: 5.0) [default=5.0].

muse_astrometry.param.niter

Number of iterations of the astrometric fit. (long; default: 2) [default=2].

muse_astrometry.param.rejsigma

Rejection sigma level of the astrometric fit. (float; default: 3.0) [default=3.0].

muse_astrometry.param.rotcenter

Center of rotation of the instrument, given as two comma-separated floating point values in pixels. (str; default: ‘-0.01,-1.20’) [default=”-0.01,-1.20”].

muse_astrometry.param.lambdamin

Cut off the data below this wavelength after loading the pixel table(s). (float; default: 4000.0) [default=4000.0].

muse_astrometry.param.lambdamax

Cut off the data above this wavelength after loading the pixel table(s). (float; default: 10000.0) [default=10000.0].

muse_astrometry.param.lambdaref

Reference wavelength used for correction of differential atmospheric refraction. The R-band (peak wavelength ~7000 Angstrom) that is usually used for guiding, is close to the central wavelength of MUSE, so a value of 7000.0 Angstrom should be used if nothing else is known. A value less than zero switches DAR correction off. (float; default: 7000.0) [default=7000.0].

muse_astrometry.param.darcheck

Carry out a check of the theoretical DAR correction using source centroiding. If “correct” it will also apply an empirical correction. (str; default: ‘none’) [default=”none”].

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

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

muse_astrometry.param.centroid = "moffat"
muse_astrometry.param.detsigma = 3.0
muse_astrometry.param.radius = 5.0
muse_astrometry.param.faccuracy = 5.0
muse_astrometry.param.niter = 2
muse_astrometry.param.rejsigma = 3.0
muse_astrometry.param.rotcenter = "-0.01,-1.20"
muse_astrometry.param.lambdamin = 4000.0
muse_astrometry.param.lambdamax = 10000.0
muse_astrometry.param.lambdaref = 7000.0
muse_astrometry.param.darcheck = "none"

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

import cpl
muse_astrometry = cpl.Recipe("muse_astrometry")
[...]
res = muse_astrometry( ..., param = {"centroid":"moffat", "detsigma":3.0})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to Peter Weilbacher. Alternatively, you may send a report to the ESO User Support Department.