Compute an astrometric solution.
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.
Create an object for the recipe muse_astrometry.
import cpl
muse_astrometry = cpl.Recipe("muse_astrometry")
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”].
Source detection sigma level to use. (float; default: 3.0) [default=3.0].
Initial radius in pixels for pattern matching identification in the astrometric field. (float; default: 5.0) [default=5.0].
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].
Number of iterations of the astrometric fit. (long; default: 2) [default=2].
Rejection sigma level of the astrometric fit. (float; default: 3.0) [default=3.0].
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”].
Cut off the data below this wavelength after loading the pixel table(s). (float; default: 4000.0) [default=4000.0].
Cut off the data above this wavelength after loading the pixel table(s). (float; default: 10000.0) [default=10000.0].
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].
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.
Please report any problems to Peter Weilbacher. Alternatively, you may send a report to the ESO User Support Department.
This file is part of the MUSE Instrument Pipeline Copyright (C) 2005, 2014 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 02111-1307 USA
Code author: Peter Weilbacher <usd-help@eso.org>