5 Pulsars as Gravitational Wave 4 Pulsar Timing4.6 Geodetic precession

4.7 Going further 

This chapter has outlined past and present progress in a number of areas related to pulsar timing. For further details on the technical details and prospects of pulsar timing, the interested reader is referred to a number of excellent review articles [269, 16, 233, 23, 24]. Two freely available software packages which are routinely used for time-of-arrival analyses by the pulsar community are available, viz. TEMPO [240Jump To The Next Citation Point In The Article, 196] and TIMAPR [72, 166]. These packages are based on more detailed versions of the timing model outlined in §  4.2 . An up-to-date list summarising the various timing programmes is kept by Don Backer [10Jump To The Next Citation Point In The Article]. An audio file and slides from a lecture on pulsar timing presented by Backer at the centennial meeting of the American Physical society is also available on-line [11]. Another relevant lecture from that meeting is Will's presentation [268] on tests of Einstein's relativity which includes an excellent overview of Taylor and Weisberg's measurements of PSR B1913+16. Kramer [120] has written a lucid review article discussing measurements of geodetic precession in binary pulsars and their implications.

The remarkable precision of these measurements, particularly for millisecond pulsars, allows the detection of radial accelerations on the pulsar induced by orbiting bodies smaller than the Earth. Alex Wolszczan detected one such ``pulsar planetary system'' in 1990 following the discovery of a 6.2-ms pulsar B1257+12. In this case, the pulsar is orbited by at least three Earth-mass bodies [273Jump To The Next Citation Point In The Article, 186, 272Jump To The Next Citation Point In The Article]. Subsequent measurements of B1257+12 were even able to measure resonance interactions between two of the planets [271Jump To The Next Citation Point In The Article], confirming the nature of the system beyond all doubt. Long-term timing measurements of the 11-ms pulsar B1620-26 in the globular cluster M4 indicate that it may also have a planetary companion [247Jump To The Next Citation Point In The Article, 15Jump To The Next Citation Point In The Article, 245Jump To The Next Citation Point In The Article]. For detailed reviews of these systems, and their implications for planetary formation scenarios, the interested reader is referred to [189].



5 Pulsars as Gravitational Wave 4 Pulsar Timing4.6 Geodetic precession

image Binary and Millisecond Pulsars at the New Millennium
Duncan R. Lorimer
http://www.livingreviews.org/lrr-2001-5
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