psphot Extended Source Fit 20130712 tag

This page discusses some experiments where we ran psphot on simulated images using the current ipp tag ipp-20130712

This can be compared to the results with the ipp trunk discussed here

The 40 simulated images were provided last year by Peter Draper for use in testing the psphot kron radius and magnitude code. They were constructed using E Bertin's SkyMaker program.

Sersic Index

If we look at the sersic index for all galaxies we get the following histogram. The hisogram on the right shows the counts for pure disks and bulges.

Sersic Fit Magnitudes

The difference between the simulated galaxies' magnitudes and the sersic fit magnitudes are shown in the following plot.

If we consider only the pure bulge sources the fits are better. psphot under estimates the flux somewhat. If we look at pure disks we see the banding.

Radii

disks

The following plot compares the measured semi-major axis with the disk scale length.

bulges

Here is a comparison of the measured width to the bulge effective radius.

Exponential Model

Exponential magnitudes

Radii

de Vaucouleurs Model