detect_sources is too slow

detect_sourcesis way too slow... not suited for Monte Carlo analysis

This is due to the subpixel=True options of photutils.find_peaks which use photutils.centroid.fit_2dgaussian.

One possible way to improve on that is to use photutils.centroid.centroid_1dg see https://github.com/astropy/photutils/blob/master/docs/centroids.rst

• create a specific branch for testing
• write/find specific test for non centered gaussian
• test actual behavior
• switch to 2 stages find_peaks(subpixel=False) + centroid_1dg