Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates - Astrophysics > Instrumentation and Methods for AstrophysicsReportar como inadecuado




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Abstract: As the quality and quantity of astrophysical data continue to improve, theprecision with which certain astrophysical events can be timed becomes limitednot by the data themselves, but by the manner, standard, and uniformity withwhich time itself is referenced. While some areas of astronomy most notablypulsar studies have required absolute time stamps with precisions ofconsiderably better than 1 minute for many decades, recently new areas havecrossed into this regime. In particular, in the exoplanet community, we havefound that the typically unspecified time standards adopted by various groupscan differ by as much as a minute. Left uncorrected, this ambiguity may bemistaken for transit timing variations and bias eccentricity measurements. Weargue that, since the commonly-used Julian Date, as well as its heliocentricand barycentric counterparts, can be specified in several time standards, it isimperative that their time standards always be reported when accuracies of 1minute are required. We summarize the rationale behind our recommendation toquote the site arrival time, in addition to using BJD TDB, the BarycentricJulian Date in the Barycentric Dynamical Time standard for any astrophysicalevent. The BJD TDB is the most practical absolute time stamp forextra-terrestrial phenomena, and is ultimately limited by the properties of thetarget system. We compile a general summary of factors that must be consideredin order to achieve timing precisions ranging from 15 minutes to 1 microsecond.Finally, we provide software tools that, in principal, allow one to calculateBJD TDB to a precision of 1 microsecond for any target from anywhere on Earthor from any spacecraft.



Autor: Jason Eastman, Robert Siverd, B. Scott Gaudi

Fuente: https://arxiv.org/







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