Period evolution of the remarkable CCO 1E 1207.4--5209

1E 1207.45209, the central compact object in the SNR PKS 120951/52, showsabsorption lines in its thermal Xray spectrum and 424 ms pulsations. Thephasecoherent timing of 14 XMMNewton and Chandra observations of 20002005resulted in two timing solutions with different signs and very small magnitudesof period derivative. The spindown solution suggests that 1E1207 is a neutronstar born with a rather low magnetic field and almost the same period as thatcurrently observed. The spinup solution could be explained by a lowrateaccretion from a supernova debris disk. To find the unique timing solution andunderstand the properties of this enigmatic object, we propose new timingobservations, which will be phaseconnected with all the previous observations. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]