this linking length, the borders of each source are automatically defined as the [*loci*]{} where the photon density is equal to the background density. We recall that the photon density still includes both the source signal and the background, since no background was subtracted from the image. With this definition, statistically the entire signal associated to the source is included in the FOF region. In other words, this choice of the linking length corresponds to a precise definition of the source boundaries, and allows us to perform aperture photometry directly inside the FOF region.

For the sources classified as extended, the regions obtained by FOF were used as photometry aperture. However, unresolved sources that are well-described by the PSF shape were treated differently. For each source classified as unresolved, we normalized the PSF to the total photon inside the core region and calculated the radius where it reaches $1/2$ the local background level. This defines the extraction radius for all unresolved sources. When two unresolved sources are closer than this radius, the overlapping pixels were assigned to the one with the brighter expected value in that position. A more sophisticated treatment including a source-fitting procedure is planned to be introduced 