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Excellent research published online: Accurate light-time correction due to a gravitating mass

Dear Colleagues,

TITLE: Accurate light-time correction due to a gravitating mass
AUTHORS: Neil Ashby, Bruno Bertotti

It gives me great pleasure to notify you of the publication of the above article in Classical and Quantum Gravity.

This article received very positive comments and a high quality rating from its referees. Please find a summary of the developments made in this article below:

The time delay and deflection of light passing between two points near a spherical mass of gravitational radius m, are expressed to second order in m in terms of endpoint positions and angle subtended at the source by the endpoints, instead of unknown quantities such as the closest approach distance b. We minimize Fermat’s action functional and solve the eikonal equation for a null geodesic. In a close superior conjunction the second-order correction contains an enhanced part of order m2R/b2, where R is of the order of the endpoint distances from the sun. We compare these results to previous calculations, in particular with the second-order terms introduced in NASA’s Orbit Determination Program. We use asymptotic series to determine which higher-order terms are important.

The results are significant for understanding the results of the Cassini light-time experiment, and for future missions whose purpose may include measuring the PPN parameter gamma.

Yours sincerely

Adam Day
Classical and Quantum Gravity