Conversion of object position(s) from matching pairs of nodded object files + sextractor tables
The files listed in the Set Of Frames (sof-file) must be tagged: Sextractor-object-file.fits POS_CONVERT Sextractor-table-file.fits POS_TABLE The table must include these columns, all with numerical data: XWIN_IMAGE, YWIN_IMAGE, FLUX_AUTO.
Such a table can be created by the source extractor software sextractor.
In addition to containing pairs of object- and table-files the SOF may also contain only object-files.
In this case the object files must be tagged with: POS_CONVERT.
For each input object frame one or more products will be created with updated WCS-ccordinates (CRPIX[12]).
When the object frame is matched with a table-frame, one product will be created for each row in the table.
Such products will be created in order of decreasing object brightness.
When the object frames are pairs of 4-beam-frames, the position (centroid) of the brightest object in the 4-beam-frame will be written into the first product.
The nodding and chopping throw will determine the position written into the second product based on the raw-frame and the position written into the two products based on the matching off-frame.
When the object frames are pairs of 4-beam-frames, the recipe also supports updating the WCS-coordinates of an auxiliary frame (e.g. error map) for each object.
If present these auxiliary frames must be tagged: Object-auxiliary.fits POS_AUX (optional).
The primary product(s) will have a FITS card ‘HIERARCH ESO PRO CATG’ with a value of: IMG_CONVERTED If created, the auxiliary products will have a FITS card ‘HIERARCH ESO PRO CATG’ with a value of: AUX_CONVERTED
Create an object for the recipe visir_util_convert_pos.
import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")
The maximum eccentricity allowed in the combination of the three (in parallel nod/chopping) or four (in perpendicular nod/chopping) beams. In parallel mode, three perfectly aligned points spaced with the chopnod throw will have eccentricity 0, while in perpedicular mode a square with the chopnod throw as the side length will have eccentricity 0 (float; default: 0.25) [default=0.25].
Number of plains to average before searching for the beam positions. (long; default: 1) [default=1].
Shift beam positions by cross correlating images. (bool; default: False) [default=False].
Shift beam positions by brightest pixel. (bool; default: True) [default=True].
Window around detected beams to use for cross correlation. (long; default: 64) [default=64].
The following code snippet shows the default settings for the available parameters.
import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")
visir_util_convert_pos.param.eccmax = 0.25
visir_util_convert_pos.param.naverage = 1
visir_util_convert_pos.param.xcorrelate = False
visir_util_convert_pos.param.brightest = True
visir_util_convert_pos.param.window = 64
You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:
import cpl
visir_util_convert_pos = cpl.Recipe("visir_util_convert_pos")
[...]
res = visir_util_convert_pos( ..., param = {"eccmax":0.25, "naverage":1})
See also
cpl.Recipe for more information about the recipe object.
Please report any problems to Lars Lundin. Alternatively, you may send a report to the ESO User Support Department.
This file is part of the VISIR Instrument Pipeline Copyright (C) 2011 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: Lars Lundin <llundin@eso.org>