AXES: Compute the Centroid of an Object in an Image

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.