tableobs is used to prepare
from tables that contain observation data. A
is the natural format in which Yafit stores information about
observed spectra, but observations are not usually originally supplied
in this form, so
tableobs should be used to prepare them
in this way. To use this task, you must have a table which contains
data from one or more observations and a key file which
describes what each column of the table means, in particular which
columns represent flux values and flux errors at which wavelengths.
The key file is an ASCII table format containing optional comment lines (blank or starting with the '#' character) followed by a series of lines each describing the observations in one band pass. Each of these lines has four space-separated entries:
xis typically a band pass central wavelength and
xWidthis the band pass full width. However, these X and Y values may be interpreted differently if desired, for instance Y may be in magnitudes rather than flux units.
Note that the Y error column may contain the special value
null" if no the input table contains no error information
for one or more Y values.
In this case however beware that error-less Y values will not be used
chi2 goodness-of-fit measure in the
since chi-squared fitting makes no sense without error estimates.
To introduce given non-null error values you should pre-process the table
(e.g. using STILTS) to provide a
column containing suitable numeric values.
The input table which the key file describes is a table in any
of the formats recognised by the SUN/256
package, including FITS, VOTable, CSV and ASCII. In general it is
necessary to say what format it is in with the
See Section 3.1 for some more discussion and examples.
Usage: tableobs [-help] [-debug] in=<table> [ifmt=<in-format>] key=<key-file> [out=<obs-file>] [redshift=<expr>] [x=<expr>] [y=<expr>] [xname=<value>] [xunit=<value>] [yname=<value>] [yunit=<value>]
ifmt = <in-format>
in = <table>
keyparameter. The table located by this parameter may be in any of the formats supported by STIL, as defined by the
key = <key-file>
out = <obs-file>
yobsfile will be written.
redshift = <expr>
x = <expr>
x" simply makes the one equal to the other, however it is possible to use algebraic expressions here in terms of
x, for instance in order to modify the scaling (change units). Normal arithmetic operators as well as some special functions may be used - see Section 6.
xname = <value>
xunit = <value>
y = <expr>
y" simpley makes the one equal to the other, however it is possible to use algebraic expressions here in terms of
x(the X values from the input key file), and any of the values in the input table referred to by their column name. Normal arithmetic operators as well as some special functions such as
abToJansky()may be used - see Section 6
yname = <value>
yunit = <value>