# A Natural Formalism for Microlensing

@article{Gould2000ANF,
title={A Natural Formalism for Microlensing},
author={Andrew P. Gould},
journal={The Astrophysical Journal},
year={2000},
volume={542},
pages={785-788}
}
• A. Gould
• Published 2000
• Physics
• The Astrophysical Journal
If the standard microlensing geometry is inverted so that the Einstein ring is projected onto the observer plane rather than the source plane, then the relations between the observables (θE,E) and the underlying physical quantities (M,πrel) become immediately obvious. Here θE and E are the angular and projected Einstein radii, M is the mass of the lens, and πrel is the lens-source relative parallax. I recast the basic formalism of microlensing in light of this more natural geometry and in terms… Expand
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#### References

SHOWING 1-10 OF 20 REFERENCES
Astrometric Observation of MACHO Gravitational Microlensing
• Physics
• 1998
Following previous suggestions of other researchers, this paper discusses the prospects for astrometric observation of MACHO gravitational microlensing events. We derive the expected astrometricExpand
Interpretation of microlensing events in Q2237 + 0305
• Physics
• 1994
We point out the uncertainties in the potential models of the foreground galaxy in the gravitational lens Q2237 + 0305. The surface densities and external shears are uncertain by a factor ofExpand
First Observation of Parallax in a Gravitational Microlensing Event
We present the first detection of parallax effects in a gravitational microlensing event. Parallax in a gravitational microlensing event observed only from the Earth appears as a distortion of theExpand
Gravitational microlensing by the galactic halo
A simple model of microlensing by massive objects that might be present in the halo of the Galaxy is presented. It is shown that in any nearby galaxy one star out of a million is strongly microlensedExpand
MICROLENSING AND THE STELLAR MASS FUNCTION
Traditional approaches to measuring the stellar mass function (MF) are fundamentally limited because objects are detected based on their luminosity, not their mass. These methods are therebyExpand
Finite source sizes and the information content of macho-type lens search light curves
• Physics
• 1994
If the dark halo matter is primarily composed of Massive Compact Halo Objects (MACHOs) toward the lower end of the possible detection range (less than 10(exp -3) solar mass) a fraction of the lensExpand
Photometric Microlens Parallaxes with the Space Interferometry Mission
• Physics
• 1999
Astrometric measurements of microlensing events can in principle determine both the "parallax" E and the "proper motion" μ of an individual event, which (combined with the Einstein timescale tE) inExpand
Binary microlensing events from the MACHO project
We present the light curves of 21 gravitational microlensing events from the first six years of the MACHO Project gravitational microlensing survey that are likely examples of lensing by binaryExpand
Combined Analysis of the Binary Lens Caustic-crossing Event MACHO 98-SMC-1
• Physics
• 1999
We fit the data for the binary lens microlensing event MACHO 98-SMC-1 from five different microlensing collaborations and find two distinct solutions characterized by binary separation d and massExpand
MACHO Alert 95-30: First Real-Time Observation of Extended Source Effects in Gravitational Microlensing
We present analysis of MACHO Alert 95-30, a dramatic gravitational microlensing event toward the Galactic bulge whose peak magnification departs significantly from the standard point-sourceExpand