  We are proposing to conduct a multicolor, synoptic infrared (IR) imaging
survey of the Northern sky with a new, dedicated 6.5-meter telescope at San
Pedro M\'artir (SPM) Observatory. This initiative is being developed in
partnership with astronomy institutions in Mexico and the University of
California. The 4-year, dedicated survey, planned to begin in 2017, will reach
more than 100 times deeper than 2MASS. The Synoptic All-Sky Infrared (SASIR)
Survey will reveal the missing sample of faint red dwarf stars in the local
solar neighborhood, and the unprecedented sensitivity over such a wide field
will result in the discovery of thousands of z ~ 7 quasars (and reaching to z >
10), allowing detailed study (in concert with JWST and Giant Segmented Mirror
Telescopes) of the timing and the origin(s) of reionization. As a time-domain
survey, SASIR will reveal the dynamic infrared universe, opening new phase
space for discovery. Synoptic observations of over 10^6 supernovae and variable
stars will provide better distance measures than optical studies alone. SASIR
also provides significant synergy with other major Astro2010 facilities,
improving the overall scientific return of community investments. Compared to
optical-only measurements, IR colors vastly improve photometric redshifts to z
~ 4, enhancing dark energy and dark matter surveys based on weak lensing and
baryon oscillations. The wide field and ToO capabilities will enable a
connection of the gravitational wave and neutrino universe - with events
otherwise poorly localized on the sky - to transient electromagnetic phenomena.
