Project

General

Profile

Flux-dependent PSF results from on-sky analysis

Slopes between half light radius and flux

We use observation of Omega Cen 180765-180786 (g-band), 180699-180720 (r-band), 180739-180764 (i-band), 180677-180698 (z-band), 180655-180676 (Y-band) to find the dependence of PSF on flux. The dependence is quantified as the slope between either FLUX_MAX and FLUX_RAD or FLUX_MAX and R50 where FLUX_MAX (maximum value of flux in the object) and FLUX_RAD (half light radius) are found from SExtractor. R50 is a flux independent measure of half light radius of stars. The attached plot shows the slopes of 61 CCDs averaged over all observations of individual filters. Each panel shows the relation for different filters. Red points show the slope between FLUX_MAX and FLUX_RAD and green color show the slope between FLUX_MAX and R50. The errors are found using jackknife method. The right panels shows the histogram of slopes. The average and std. deviation of the distributions are also shown.

The distribution of R50 for the stars used in the analysis are shown. It can be seen that g-band distribution is significantly different from the rest of the filters. I am planning to run the code on images of different seeing to test the dependence on seeing.