SIMBAD references

Multifrequency observations of the planet pulsar PSR B1257+12 have been made to examine a possibility that the 25.3 day periodicity observed in its pulse timing residuals represents a variable delay generated by solar rotation-induced density fluctuations in the solar wind. New timing measurements of the pulsar show that the amplitude of these residuals is frequency independent, implying that the periodicity cannot be caused by any arrival time delays related to the pulse propagation through an ionized medium. Therefore, in agreement with the original assumption, the observed 25.3 day pulse timing periodicity is most plausibly explained in terms of the orbital motion of a low-mass planet around the pulsar.