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

14.2. CVF IMAGE ANALYSIS 117
CIA> restore, ’$cia_vers/test/raster_m51_lw3_oct01.xdr’
CIA> photom_psf, raster, psf_flux, x_out, y_out, 11,25,image=8, $
background=background, bsize=5
CIA> print, psf_flux, x_out, y_out, background
302.396 11.1429 24.4762 6.83221
photom aper High level routine to perform aperture photometry.
Calling syntax:
CIA> photom_aper, raster, aper_flux, 13, 83, radius=7
CIA> print, aper_flux
556.184
As NGC 5195 isn’t a point-source, the flux derived by PSF-fitting is lower than the flux
derived by aperture photometry.
14.2 CVF image analysis
14.2.1 cvf display
cvf display is a widget program which you can use to calculate a CVF spectrum. Assuming
that you have a calibrated CVF PDS 1 ,thencvf display can be simply invoked with:
CIA> cvf_display, cvf_pds, flux=cvf_spectrum
A single window will appear with an image display subwindow and a plotting subwindow
– see Figure 14.2. A mean of the EXPOSUREs in the CVF PDS field .IMAGE is initially
displayed.
1. Clicking on a pixel will display its spectrum (arbitrary flux units against wavelength (microns))
in the plotting subwindow.
2. Clicking on a point on the plot with the right mouse button will display the EXPOSURE
at that wavelength.
3. A region of an EXPOSURE can be selected and the mean spectrum of its pixels plotted.
Click on a pixel in the EXPOSURE with the middle mouse button and then release the
button over another pixel. A mean spectrum of the subarray defined by these pixels will
be displayed.
4. If you have kept the SAD created by get sscdcvf when you first made the CVF PDS,
then the current spectrum in the plot window can be placed in the SAD substructure,
.CSSP. Click on Update SAD andwhenyouexitcvf display you will find .CSSP filled:
1 See Section 15.5.3 for a description of the CVF PDS data structure and Section 13.4.2 for an introduction to
calibrating a CVF observation.