In each obiwan/ directory write one hdf5 (id, width_x,width_y) file for each simulated source that gets injected into the brick. these should be used to
make a single coadd that is the coadd image + all simulated randoms (read and added from the hdf5 file) from all chunks
In each obiwan/ directory write one hdf5 (id, width_x,width_y) file for each simulated source that gets injected into the brick. these should be used to