We report our measurements for orbital and spin parameters of X 1822-371 using its X-ray partial eclipsing profile and pulsar timing from data collected by the Rossi X-ray Timing Explorer ( RXTE ) .
Four more X-ray eclipse times obtained by the RXTE 2011 observations were combined with historical records to trace evolution of orbital period .
We found that a cubic ephemeris likely better describes evolution of the X-ray eclipse times during a time span of about 34 years with a marginal second order derivative of \ddot { P } _ { orb } = ( -1.05 \pm 0.59 ) \times 10 ^ { -19 } s ^ { -1 } .
Using the pulse arrival time delay technique , the orbital and spin parameters were obtained from RXTE observations from 1998 to 2011 .
The detected pulse periods show that the neutron star in X 1822-371 is continuously spun-up with a rate of \dot { P } _ { s } = ( -2.6288 \pm 0.0095 ) \times 10 ^ { -12 } s s ^ { -1 } .
Evolution of the epoch of the mean longitude l = \pi / 2 ( i.e . T _ { \pi / 2 } ) gives an orbital period derivative value consistent with that obtained from the quadratic ephemeris evaluated by the X-ray eclipse but the detected T _ { \pi / 2 } values are significantly and systematically earlier than the corresponding expected X-ray eclipse times by 90 \pm 11 s. This deviation is probably caused by asymmetric X-ray emissions .
We also attempted to constrain the mass and radius of the neutron star using the spin period change rate and concluded that the intrinsic luminosity of X 1822-371 is likely more than 10 ^ { 38 } ergs s ^ { -1 } .