Osculating Versus Intersecting Circles in Space-Based Microlens Parallax Degeneracies. (arXiv:1905.06770v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gould_A/0/1/0/all/0/1">Andrew Gould</a> (MPIA, OSU)
I investigate the origin of arc degeneracies in satellite microlens parallax
pi_E measurements with only late time data, e.g., t > t0 + t_E as seen from the
satellite. I show that these are due to partial overlap of a series of
osculating, exactly circular, degeneracies in the pi_E plane, each from a
single measurement. In events with somewhat earlier data, these long arcs break
up into two arclets, or (with even earlier data) two points, because these
earlier measurmeents give rise to intersecting rather than osculating circles.
The two arclets (or points) then constitute one pair of degeneracies in the
well-known four-fold degeneracy of space-based microlens parallax. Using this
framework of intersecting circles, I show that next-generation microlens
satellite experiments could yield good pi_E determinations with only about five
measurements per event, i.e., about 30 observations per day to monitor 1500
events per year. This could plausibly be done with a small (hence cheap, in the
spirit of Gould & Yee 2012) satellite telescope, e.g., 20 cm.
I investigate the origin of arc degeneracies in satellite microlens parallax
pi_E measurements with only late time data, e.g., t > t0 + t_E as seen from the
satellite. I show that these are due to partial overlap of a series of
osculating, exactly circular, degeneracies in the pi_E plane, each from a
single measurement. In events with somewhat earlier data, these long arcs break
up into two arclets, or (with even earlier data) two points, because these
earlier measurmeents give rise to intersecting rather than osculating circles.
The two arclets (or points) then constitute one pair of degeneracies in the
well-known four-fold degeneracy of space-based microlens parallax. Using this
framework of intersecting circles, I show that next-generation microlens
satellite experiments could yield good pi_E determinations with only about five
measurements per event, i.e., about 30 observations per day to monitor 1500
events per year. This could plausibly be done with a small (hence cheap, in the
spirit of Gould & Yee 2012) satellite telescope, e.g., 20 cm.
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