How do I obtain the total luminosity for truncation models?
• First, generate a model by using “galfit -o3 filename”, where “filename” is the best GALFIT input file. This will produce an image block called “subcomps.fits,” where each model is placed into its own image slice. To obtain the total luminosity, all it takes is to sum up the flux in the image slice of the truncated component. One can do so in IRAF really easily by doing “imstat subcomps[nn]” where nn is the slice of the model component. The total flux is then the mean flux of the image multiplied by the total number of pixels in the image. The only catch to this process is that the fitting region of the image has to be sufficiently large, or else the image boundary will cut off the model. But, one can deal with this in the GALFIT menu by adjusting the fitting region and the centroid of the model components. Why does the GALFIT iteration, i.e. “countdown”, clock keep bouncing up and down? GALFIT has to know when to stop iterating. The ideal situation is when Chi2 changes by
