sapertures -- Set or change aperture header information
- List of spectral images to be modified.
- apertures = ""
- List of apertures to be modified. The null list selects all apertures. A list consists of comma separated numbers and ranges of numbers. A range is specified by a hyphen. An optional step size may be given by using the x followed by a number. See xtools.ranges for more information.
- apidtable = ""
- Aperture table. This may be either a text file or an image.
A text file consisting of lines with an aperture number,
beam number, dispersion type code, coordinate of the first physical
pixel, coordinate interval per physical pixel, redshift factor,
lower extraction aperture position, upper extraction aperture position,
and aperture title or identification. An image will contain the
keywords SLFIBnnn with string value consisting of aperture number,
beam number, optional right ascension and declination, and aperture title.
Any field except the aperture number may be given the value INDEF to
indicate that the value is not to be changed from the current value. Any
apertures not in this table are assigned the values given by the task
parameters described below.
As a special case a file having just the aperture number, beam number, and spectrum aperture identification may be used. This file format as well as use of an image header is the same as that in the apextract package.
- wcsreset = no
- Reset the world coordinate system (WCS) of the selected apertures to uncorrected pixels. If this parameter is set the apidtable and task aperture parameters are ignored. This option sets the dispersion type flag to -1, the starting coordinate value to 1, the interval per pixel to 1, and no redshift factor and leaves the other parameters unchanged. The option is useful when it is desired to apply a second dispersion correction using identify and dispcor .
- verbose = no
- Print a record of each aperture modified? Only those apertures in which the beam number or label are changed are printed.
If no aperture table is specified or if there is not an aperture entry in the table for a selected aperture the following parameter values are used. A value of INDEF will leave the corresponding parameter unchanged.
- beam = INDEF
- Beam number.
- dtype = INDEF
- Dispersion type. The dispersion types are:
-1 Linear with dispersion correction flag off 0 Linear with dispersion correction flag on 1 Log-linear with dispersion correction flag on
- w= INDEF
- Coordinate of the first physical pixel. Note that it is possible that the physical pixels are not the same as the logical pixels if an image section has been extracted.
- dw = INDEF
- Coordinate interval per physical pixel. Note that it is possible that the physical pixels intervals are not the same as the logical pixels intervals if an image section has been extracted.
- z = INDEF
- Redshift factor. This is usually set with the task dopcor . Coordinates are divided by one plus the redshift factor (1+z).
- aplow = INDEF, aphigh = INDEF
- The aperture extraction limits. These are set when the apextract package is used and it is unlikely that one would use this task to change them.
- title = INDEF
- Aperture title or identification string.
This task sets or changes any of the aperture specific parameters except the aperture number and the number of valid pixels. It is particularly useful for images which use the "multispec" world coordinate system attribute strings which are not readily accessible with other header editors. A list of images and a list of apertures is used to select which spectra are to be modified. The default empty string for the apertures selects all apertures. The new values are specified either in an aperture table file or with task parameters. The aperture table is used to give different values to specific apertures. If all apertures are to have the same values this file need not be used.
The aperture parameters which may be modified are the beam number, the dispersion type, the coordinate of the first physical pixel, the coordinate interval per physical pixel, the redshift factor, the aperture extraction limits, and the title. The task has parameters for each of these and the aperture table consists of lines starting with an aperture number followed by the above parameters in the list order and separated by whitespace. As a special case the aperture table may be a file abbreviated to aperture number, beam number, and title or an image with keywords SLFIBnnn containing the aperture number, beam number, optional right ascension and declination, and title. These special cases allow use of the same file orimage used in the apextract package. If any of the parameters are specified as INDEF then the value will be unchanged.
If the wcsreset parameter is set then the aperture table and task aperture parameters are ignored and the selected apertures are reset to have a dispersion type of -1, a starting coordinate of 1, a coordinate interval of 1, and a redshift factor of 0. This other parameters are not changed. These choice of parameters has the effect of resetting the spectrum to physical pixel coordinates and flagging the spectra as not being dispersion calibrated. One use of this option is to allow the dispcor task to be reapplied to previously dispersion calibrated spectra.
The verbose parameter lists the old and new values when there is a change. If there are no changes there will be no output.
1. To add titles to a multifiber extraction and change one of the beam numbers:
cl> type m33aps 36 2 Henear 37 0 Sky 38 1 New title 39 1 Another title 41 0 Sky 42 1 Yet another title 43 1 YAT 44 1 Was a sky but actually has an object 45 1 Wow 46 1 Important new discovery 47 0 Sky 48 2 Henear cl> saper m33.ms apid=m33aps v+ demoobj1.ms: Aperture 37: --> Sky Aperture 38: --> New title Aperture 39: --> Another title Aperture 41: --> Sky Aperture 42: --> Yet another title Aperture 43: --> YAT Aperture 44: beam 0 --> beam 1 Aperture 44: --> Was a sky but actually has an object Aperture 45: --> Wow Aperture 46: --> Important new discovery Aperture 47: --> Sky
2. To reset a dispersion calibrated multifiber spectrum:
cl> saper test.ms wcsreset+ verbose+ test.ms: Aperture 1: w1 4321. --> 1. dw 1.23 --> 1. Aperture 2: w1 4321. --> 1. dw 1.23 --> 1. <etc.>
3. To set a constant wavelength length scale (with the default parameters):
cl> saper test.ms dtype=0 w1=4321 dw=1.23 v+ test.ms: Aperture 1: w1 1. --> 4321. dw 1. --> 1.23 Aperture 2: w1 1. --> 4321. dw 1. --> 1.23 <etc.>
4. To reset the wavelengths and title of only aperture 3:
cl> saper test.ms aper=3 w1=4325 dw=1.22 title=HD12345 v+ test.ms: Aperture 3: w1 4321. --> 4325. dw 1.23 --> 1.22 apid --> HD12345
- SAPERTURES V2.11
- This task has been modified to allow use of image header keywords as done in the APEXTRACT package.
- SAPERTURES V2.10.3
- This task has been greatly expanded to allow changing any of the WCS parameters as well as the beam number and aperture title.
- SAPERTURES V2.10
- This task is new.