Complex sentence: The hyperluminous quasar APM 08279 +5255 was, when discovered in 1998, given an absolute magnitude of − 32.2, although high resolution imaging with the Hubble Space Telescope and the 10 m Keck Telescope revealed that this system is gravitationally lensed.
Split into simpler sentences: The hyperluminous quasar APM 08279 +5255 was, when discovered in 1998, given an absolute magnitude of − 32.2. High resolution imaging with the Hubble Space Telescope and the 10 m Keck Telescope revealed that this system is gravitationally lensed.