The ESP application CORR generates a cross-correlation image by correlating a mask with the input image. As with SELFC, you again input a size but in this case it defines the scale length of the galaxy for which the correlation should be optimised. The radius of the circular exponential mask used (simulating a face on galaxy) with which the image will be correlated is varied accordingly. It should be noted that this optimisation is such that the correlation will still be sensitive to objects of scale lengths in the approximate range 0.25 to 4 times the scale length requested.
The correlation results placed in the output image generated are normalised to the range 0-1. If no arbitrary value of correlation coefficient is being employed to define the reality of a detection, a suitable value may be derived using the method described for SELFC.
The application can be used with the following syntax:
% corr in=hh1826 out=correl scale=8. psize=0.3 back=3265 useall=true
Correlates image hh1826 with a mask-template optimised for galaxies of
8 arc second scale length. The image pixel size is .3 arc seconds
per pixel and the background value is 3265. The
output cross-correlation image will be called correl.
ESP --- Extended Surface Photometry