A flippant googling suggests the Sun outputs 10^45 photons per second. The very bright object in question is a galaxy consisting of, we can presume, a few order

A flippant googling suggests the Sun outputs 10^45 photons per second. The very bright object in question is a galaxy consisting of, we can presume, a few orders of magnitude more than 10^6 stars. Upshot is that the Hubble Telescope should be receiving a few hundred or thousand photons from that galaxy every second. In comparison and for scale, IIRC the human eye has been shown capable of detecting individual photons.