With an optical R -band magnitude of 15.2 , the recently discovered z =3.911 BAL quasar APM 08279+5255 is an exceptionally bright high redshift source .
Its brightness has allowed us to acquire a high signal-to-noise ratio { ( \sim 80 ) } , high resolution ( \sim 6 km s ^ { -1 } ) spectrum using the HIRES echelle spectrograph on the 10-m Keck I telescope .
Given the quality of the data , these observations provide an unprecedented view of associated and intervening absorption systems .
Here we announce the availability of this spectrum to the general astronomical community and present a brief analysis of some of its main features .