Source Finding

find_sources() is an iterative source-finding algorithm that uses peak detection on a TS map to find new source candidates. The procedure for adding new sources at each iteration is as follows:

  • Generate a TS map for the test source model defined with the model argument.
  • Identify peaks with sqrt(TS) > sqrt_ts_threshold and an angular distance of at least min_separation from a higher amplitude peak in the map.
  • Order the peaks by TS and add a source at each peak starting from the highest TS peak. Set the source position by fitting a 2D parabola to the log-likelihood surface around the peak maximum. After adding each source, re-fit its spectral parameters.
  • Add sources at the N highest peaks up to N = sources_per_iter.

Source finding is repeated up to max_iter iterations or until no peaks are found in a given iteration. Sources found by the method are added to the model and given designations PS JXXXX.X+XXXX according to their position in celestial coordinates.


model = {'Index' : 2.0, 'SpatialModel' : 'PointSource'}
srcs = gta.find_sources(model=model, sqrt_ts_threshold=5.0,

The method for generating the TS maps can be controlled with the tsmap_fitter option. TS maps can be generated with either tsmap() or tscube().