paper

Photon Statistics Limits for Earth-Based Parallax Measurements of MACHO Events

arXiv:astro-ph/9503039 · doi:10.1086/177953

Abstract

We analyze the limitations imposed by photon counting statistics on extracting useful information about MACHOs from Earth-based parallax observations of microlensing events. We find that if one or more large (say ) telescopes are dedicated to observing a MACHO event for several nights near maximum amplification, then it is possible, in principle, to measure the velocity of the MACHO well enough to distinguish between disk and halo populations for events with $ω{A_m}\!^2 \gta 1\,\rm day^{-1}$, where denotes the timescale of the event and denotes its maximum amplification. Thus, if it turns out to be possible to reduce all other sources of error to below that of photon statistics, it may be feasible to do useful Earth-based parallax observations for high amplification events.

10 pages; LaTeX. one figure available upon request to [email protected]. REVISED: Error in impact parameter distribution of MACHO events (which had led to an underestimate of the expected fraction of high amplification events) was corrected; two references were added.

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