Precise timing of the X-ray pulsar 1E 1207.4-5209: A steady neutron star weakly magnetized at birth

We analyze all X- ray timing data on 1E 1207.4 - 5209 in supernova remnant PKS 1209 - 51/ 52 gathered from 1993 - 2005 and find a highly stable rotation with P = 424.130749(4) ms and P = (606 +/- 9.0) x 10(-17) ( 1 sigma errors). This refutes previous claims of large timing irregularities in these data. In the dipole spin-down formalism, the 2 sigma upper limit on P implies a spin-down luminosity E < 1.3 x 10(32) ergs s(-1), surface magnetic field strength B-p < 3.3 x 10(11) G, and characteristic age tau(c) P/2P > 27 Myr. This tau(c) exceeds the remnant age by 3 orders of magnitude, requiring that the pulsar was born spinning at its present period. The X- ray luminosity of 1E 1207.4 - 5209, L-bol approximate to 2x10(33) (d/2 kpc)(2) ergs s(-1), exceeds its E, implying that L-bol derives from residual cooling and perhaps partly from accretion of supernova debris. The upper limit on B-p is small enough to favor the electron- cyclotron model for at least one of the prominent absorption lines in its soft X- ray spectrum. This is the second demonstrable case of a pulsar born spinning slowly and with a weak B- field, after PSR J1852 + 0040 in Kesteven 79. We suggest that these properties define the class of central compact objects.