The total magnification due to a point lens has been of particular interest as the theorem that gravitational lensing results in light amplification for all observers appears to contradict the conservation of photon number. This has been discussed several times, and various resolutions have been offered. In this note, we use a kinematic approach to provide a formula for the magnification factor for the primary image accurate to first order and valid for rays leaving the source at any trajectory. We thus determine the magnification over a sphere surrounding the system. A new result found is that while the magnification dips below unity far from the optical axis as noted by others, it returns to unity directly behind the source.

Item Type:	Refereed Article
Keywords:	mathematical models, planet detection, gravitation, gravitational lensing: micro, methods: numerical, acceleration of particles, gravitational lensing: strong
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Stellar astronomy and planetary systems
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Walters, SJ (Mr Stephen Walters)
UTAS Author:	Forbes, LK (Professor Larry Forbes)
ID Code:	106701
Year Published:	2015
Funding Support:	Australian Research Council (DP140100094)
Deposited By:	Mathematics and Physics
Deposited On:	2016-02-17
Last Modified:	2017-11-01
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