An astronomer. Some programs for new objects and activity are for patrolling galaxies for supernovae, others are for gamma ray bursters, others for NEOs (near earth objects), others for dark energy, dark matter, black holes, extra-solar planets, some for outbursts from irregular variable stars, solar activity, planetary and Moon transcient phenomena, planetary geophysics, orbital mechanics, radio and radar astronomy, and exobiology. I left out cosmology, spectrophotometry, interstellar gas molecule and particle investigations, stellar evolution, galactic evolution, planetary geophysics and chemistry because those are about known objects.
Both amateurs and professionals do most of the above activities.