Abstract
Pulsar positions can be measured with high precision using both pulsar
timing methods and very long baseline interferometry (VLBI). Pulsar
timing positions are referenced to a solar-system ephemeris, whereas
VLBI positions are referenced to distant quasars. Here, we compare
pulsar positions from published VLBI measurements with those obtained
from pulsar timing data from the Nanshan and Parkes radio telescopes in
order to relate the two reference frames. We find that the timing
positions differ significantly from the VLBI positions (and also differ
between different ephemerides). A statistically significant change in
the obliquity of the ecliptic of 2.16 ± 0.33 mas is found for the
JPL ephemeris DE405, but no significant rotation is found in subsequent
JPL ephemerides. The accuracy with which we can relate the two frames is
limited by the current uncertainties in the VLBI reference source
positions and in matching the pulsars to their reference source. Not
only do the timing positions depend on the ephemeris used in computing
them, but also different segments of the timing data lead to varying
position estimates. These variations are mostly common to all
ephemerides, but slight changes are seen at the 10 μas level between
ephemerides.
Original language | English |
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Pages (from-to) | 425-434 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 469 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Jul 2017 |