We report long-term simultaneous optical and ( RXTE ) X-ray observations of the soft X-ray transient and low mass X-ray binary X1608 - 52 spanning from 1999 to 2001 .
In addition to the usual X-ray outburst and quiescent states , X1608 - 52 also exhibits an extended low intensity state during which the optical counterpart , QX Nor , is found to be about two magnitudes brighter than during quiescence .
We detect optical photometric variability on a possible period of 0.5370 days with a semi-amplitude of \sim 0.27 mag in the I band .
The modulation could be orbital but is also consistent with a scenario invoking a superhump with decreasing period .
We discuss the possibilities to distinguish between the orbital and superhump period cases .
Observations of QX Nor during quiescence indicate an F to G type main sequence secondary while theoretical considerations argue for an evolved mass donor .
Only an evolved mass donor would satisfy the condition for the occurrence of superhumps .