muse_flat(7) Combine several separate flat images into one master flat file, trace slice locations, and locate dark pixels.

SYNOPSIS

esorex muse_flat [OPTIONS] FILE.sof

DESCRIPTION

This recipe combines several separate flat-field images into one master flat-field file and traces the location of the slices on the CCD. The master flat contains the combined pixel values of the raw flat exposures, with respect to the image combination method used, normalized to the mean flux. The trace table contains polynomials defining the location of the slices on the CCD. Processing trims the raw data and records the overscan statistics, subtracts the bias (taking account of the overscan, if --overscan is not &none&), and optionally, the dark from each raw input image, converts them from adu to count, scales them according to their exposure time, and combines the exposures using input parameters. To trace the position of the slices on the CCD, their edges are located using a threshold method. The edge detection is repeated at given intervals thereby tracing the central position (the mean of both edges) and width of each slit vertically across the CCD. Deviant positions of detections on CCD rows can be detected and excluded before fitting a polynomial to all positions measured for one slice. The polynomial parameters for each slice are saved in the output trace table. Finally, the area between the now known slice edges is searched for dark (and bright) pixels, using statistics in each row of the master flat.

OPTIONS

--nifu <long>
IFU to handle. If set to 0, all IFUs are processed serially. If set to -1, all IFUs are processed in parallel. (long; default: 0). The full name of this option for the EsoRex configuration file is muse.muse_flat.nifu [default = 0].
--overscan <str>
If this is "none", stop when detecting discrepant overscan levels (see ovscsigma), for "offset" it assumes that the mean overscan level represents the real offset in the bias levels of the exposures involved, and adjusts the data accordingly; for "vpoly", a polynomial is fit to the vertical overscan and subtracted from the whole quadrant. (str; default: 'vpoly'). The full name of this option for the EsoRex configuration file is muse.muse_flat.overscan [default = vpoly].
--ovscreject <str>
This influences how values are rejected when computing overscan statistics. Either no rejection at all ("none"), rejection using the DCR algorithm ("dcr"), or rejection using an iterative constant fit ("fit"). (str; default: 'dcr'). The full name of this option for the EsoRex configuration file is muse.muse_flat.ovscreject [default = dcr].
--ovscsigma <float>
If the deviation of mean overscan levels between a raw input image and the reference image is higher than |ovscsigma x stdev|, stop the processing. If overscan="vpoly", this is used as sigma rejection level for the iterative polynomial fit (the level comparison is then done afterwards with |100 x stdev| to guard against incompatible settings). Has no effect for overscan="offset". (float; default: 30.0). The full name of this option for the EsoRex configuration file is muse.muse_flat.ovscsigma [default = 30.0].
--ovscignore <long>
The number of pixels of the overscan adjacent to the data region of the CCD that are ignored when computing statistics or fits. (long; default: 3). The full name of this option for the EsoRex configuration file is muse.muse_flat.ovscignore [default = 3].
--combine <str>
Type of combination to use (str; default: 'sigclip'). The full name of this option for the EsoRex configuration file is muse.muse_flat.combine [default = sigclip].
--nlow <long>
Number of minimum pixels to reject with minmax (long; default: 1). The full name of this option for the EsoRex configuration file is muse.muse_flat.nlow [default = 1].
--nhigh <long>
Number of maximum pixels to reject with minmax (long; default: 1). The full name of this option for the EsoRex configuration file is muse.muse_flat.nhigh [default = 1].
--nkeep <long>
Number of pixels to keep with minmax (long; default: 1). The full name of this option for the EsoRex configuration file is muse.muse_flat.nkeep [default = 1].
--lsigma <float>
Low sigma for pixel rejection with sigclip (float; default: 3.0). The full name of this option for the EsoRex configuration file is muse.muse_flat.lsigma [default = 3.0].
--hsigma <float>
High sigma for pixel rejection with sigclip (float; default: 3.0). The full name of this option for the EsoRex configuration file is muse.muse_flat.hsigma [default = 3.0].
--scale <bool>
Scale the individual images to a common exposure time before combining them. (bool; default: True). The full name of this option for the EsoRex configuration file is muse.muse_flat.scale [default = True].
--normalize <bool>
Normalize the master flat to the average flux (bool; default: True). The full name of this option for the EsoRex configuration file is muse.muse_flat.normalize [default = True].
--trace <bool>
Trace the position of the slices on the master flat (bool; default: True). The full name of this option for the EsoRex configuration file is muse.muse_flat.trace [default = True].
--nsum <long>
Number of lines over which to average when tracing (long; default: 32). The full name of this option for the EsoRex configuration file is muse.muse_flat.nsum [default = 32].
--order <long>
Order of polynomial fit to the trace (long; default: 5). The full name of this option for the EsoRex configuration file is muse.muse_flat.order [default = 5].
--edgefrac <float>
Fractional change required to identify edge when tracing (float; default: 0.5). The full name of this option for the EsoRex configuration file is muse.muse_flat.edgefrac [default = 0.5].
--losigmabadpix <float>
Low sigma to find dark pixels in the master flat (float; default: 5.0). The full name of this option for the EsoRex configuration file is muse.muse_flat.losigmabadpix [default = 5.0].
--hisigmabadpix <float>
High sigma to find bright pixels in the master flat (float; default: 5.0). The full name of this option for the EsoRex configuration file is muse.muse_flat.hisigmabadpix [default = 5.0].
--samples <bool>
Create a table containing all tracing sample points. (bool; default: False). The full name of this option for the EsoRex configuration file is muse.muse_flat.samples [default = False].
--merge <bool>
Merge output products from different IFUs into a common file. (bool; default: False). The full name of this option for the EsoRex configuration file is muse.muse_flat.merge [default = False].

Note that it is possible to create a configuration file containing these options, along with suitable default values. Please refer to the details provided by the 'esorex --help' command.

VERSION

muse_flat 1.6.2

AUTHOR

Peter Weilbacher (based on Joris Gerssen's draft) <[email protected]>

BUG REPORTS

Please report any problems to [email protected] Alternatively, you may send a report to the ESO User Support Department <[email protected]>.

LICENSE

This file is part of the MUSE Instrument Pipeline Copyright (C) 2005, 2015 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