- Form:AXES source [BOX=n] [SKY=s] [W=w1,w2] (redirection) [SILENT]
-
- source
- is the image that AXES uses.
- BOX=n
- specifies the section of the image used.
- SKY=s
- specifies the sky value used in the calculation.
- W=
- finds the centroid in a specified interval
of a wavelength-calibrated spectrum (for use
with emission spectra, NOT absorption spectra.)
- SILENT
- suppresses terminal output
This command will find the centroid of an object within the specified box
in the source image, or in the entire image if no box specifier is
given. The centroid coordinates are loaded into VISTA variables AXR and
AXC, and are also held in a common block for use by other routines. If the
W= keyword is used, the wavelength of the centroid of the spectrum in the
given interval is loaded into the variable WAVE.
The routine uses the highest pixel value on the box perimeter as a
threshold value for the centroid, unless the SKY word is given, in which
case the argument of the SKY word is taken as the threshold. The threshold
is subtracted from each pixel in the box during the calculation.
The output of AXES can be redirected.
Examples:
- AXES 3
- finds the centroid of the object in buffer 3.
- AXES 4 BOX=5
- finds the centroid of the part of
object 4 that is in box 5.
- AXES 1 W=6550,6800
- finds the centroid of the part of
the wavelength calibrated spectrum that lies between wavelengths 6550
and 6800 Angstroms.
- AXES 3 >AXES.OUT
- does the same as the first example,
but prints the result of the calculation on the file AXES.OUT,
instead of on the terminal.
- AXES 3 SILENT
- does the same as the first example,
but does not print output.