ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

114 CHAPTER 14. IMAGE ANALYSIS AND DISPLAY
The xsnr window presents three subwindows to the user. Two contain a display of the noise
region selected and of the signal region selected. Selection of these regions can be made with
sliders. The third subwindow displays the full image (the first in a cube) with both noise and
signal regions indicated by a white box. Clicking on the button Calcul with calculate the ratio
of the signal and noise in each region.
14.1.2 Energy radial profile
An estimation of the energy radial profile of a source may be done with the widget-based program
xradial.
CIA> radial_profile=xradial(raster_pds.raster)
The brightest pixel in the image is automatically selected and the user may interactively set
the radius of the disk around that pixel, from which the profile is taken, with a slider. The
integrate button toggles on/off integration of the profile.
Calculated data are displayed in a subwindow of the widget and is also the output of the
function. In the preceding example radial profile contains these data when xradial is quitted.
To reproduce the profile, try:
CIA> plot, radial_profile
14.1.3 Estimating the total source flux
The routine flux sum will help estimate the total flux from a point source and the background
level in the image. Upon calling, it displays a plot window of integrated flux against distance
from source. The user selects the interval for the background fit and enters it upon request.
An example call to flux sum could be:
CIA> flux_sum,cvf_pds.image(*,*,2),flux,flux_rms,background,background_rms
CIA> print, flux, background
In the example, the input argument is the 3rd image in the .IMAGE of a PDS. The subsequent
arguments are outputs and return the estimated flux, the RMS on the flux, the estimated
background level and the RMS on the background.
14.1.4 Photometry measurements with xphot
xphot is a photometry tool specifically designed to work with CAM data. A detailed description
of xphot can be found in Sauvage & Aussel 1997. Here we will give a simple walk-through
example.
1. Invoke xphot with...
CIA> xphot, raster_pds.raster
As you might guess from the syntax above, we are going to perform photometry on the
MOSAIC of a raster PDS. You can supply any kind of CAM image to xphot – though
you may prefer it to contain a source. If you wish to do PSF fitting and the theoretical
PSFs (see Section 15.4.1 for a description) have not been installed in the correct location
then you can specify an alternate path with the keyword psf dir: