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R. D. Ferdman, I. H. Stairs (University of British Columbia), D. C. Backer, R. Ramachandran, P. Demorest (UC Berkeley), D. J. Nice (Princeton University), A. G. Lyne, M. Kramer, D. Lorimer, M. McLaughlin (Jodrell Bank Observatory), D. Manchester (ATNF-CSIRO), F. Camilo (Columbia University), N. D'Amico, A. Possenti, M. Burgay (INAF), B. C. Joshi (National Centre for Radio Astrophysics (India)), P. C. Freire (NAIC)
The highest precision pulsar timing is achieved by reproducing as accurately as possible the pulse profile as emitted by the pulsar, in high signal-to-noise observations. The best profile reconstruction can be accomplished with several-bit voltage sampling and coherent removal of the dispersion suffered by pulsar signals as they traverse the interstellar medium. The Arecibo Signal Processor (ASP) and its counterpart the Green Bank Astronomical Signal Processor (GASP) are flexible, state-of-the-art wide-bandwidth observing systems, built primarily for high-precision long-term timing of millisecond and binary pulsars. ASP and GASP are in use at the 300-m Arecibo telescope in Puerto Rico and the 100-m Green Bank Telescope in Green Bank, West Virginia, respectively, taking advantage of the enormous sensitivities of these telescopes. These instruments result in high-precision science through 4 and 8-bit sampling and perform coherent dedispersion on the incoming data stream in real or near-real time. This is done using a network of personal computers, over an observing bandwidth of 64 to 128 MHz, in each of two polarizations.
We present preliminary results of timing and polarimetric observations with ASP/GASP for several pulsars, including the recently-discovered relativistic double-pulsar binary J0737-3039. These data are compared to simultaneous observations with other pulsar instruments, such as the new "spigot card" spectrometer on the GBT and the Princeton Mark IV instrument at Arecibo, the precursor timing system to ASP. We also briefly discuss several upcoming observations with ASP/GASP.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.