Let's say I'm using a service like TOPCAT or Vizier's cross-matching service and I'm trying to match the RA and dec of the sources in Catalogue 1, with 100,000 sources, to those in Catalogue 2, with a million sources.
How does the algorithm deal with the difference in size when it gets to the end of the shortest catalogue? Does it loop around? Or am I making an incorrect assumption about how cross-matching works?
This question comes from my attempts at making my own algorithm using astropy
's SkyCoord
function; it won't let me broadcast together two differently-sized arrays.