This paper presents an analysis of a Keck HIRES spectrum of the QSO FIRST J104459.6+365605 , covering the rest wavelength range from 2260 to 2900 Å .
The line of sight towards the QSO contains two clusters of outflowing clouds that give rise to broad blue shifted absorption lines .
The outflow velocities of the clouds range from –200 to –1200 km s ^ { -1 } and from –3400 to –5200 km s ^ { -1 } , respectively .
The width of the individual absorption lines ranges from 50 to more than 1000 km s ^ { -1 } .

The most prominent absorption lines are those of Mg ii , Mg i , and Fe ii , and Mn ii is also present .
The low ionization absorption lines occur at the same velocities as the most saturated Mg ii lines , showing that the Fe ii , Mg i and Mg ii line forming regions must be closely associated .
Many absorption lines from excited states of Fe ii are present , allowing a determination of the population of several low lying energy levels .
The populations of the excited levels are found to be considerably smaller than expected for LTE , and imply an electron density in the Fe ii line forming regions of n _ { e } \sim 4 \times 10 ^ { 3 } cm ^ { -3 } .

Modelling the ionization state of the absorbing gas with this value of the electron density as a constraint , we find that the distance between the Fe ii and Mg i line forming region and the continuum source is \sim 7 \times 10 ^ { 2 } parsec .
From the correspondence in velocity between the Fe ii , Mg i and Mg ii lines we infer that the Mg ii lines must be formed at the same distance .
The Mg ii absorption fulfills the criteria for Broad Absorption Lines defined by Weymann et al .
( 1991 ) .
Therefore the distance we find between the Mg ii line forming region and the continuum source is surprising , since BALs are generally thought to be formed in outflows at a much smaller distance from the nucleus .