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The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, the Japan Aerospace Exploration Agency. JASMINE has two main science goals. One is Galactic archaeology with a Galactic Center survey, which aims to reveal the Milky Way’s central core structure and formation history from Gaia-level (∼25 ${\mu} $as) astrometry in the near-infrared (NIR) Hwband (1.0–1.6 ${\mu} $m). The other is an exoplanet survey, which aims to discover transiting Earth-like exoplanets in the habitable zone from NIR time-series photometry of M dwarfs when the Galactic Center is not accessible. We introduce the mission, review many science objectives, and present the instrument concept. JASMINE will be the first dedicated NIR astrometry space mission and provide precise astrometric information on the stars in the Galactic Center, taking advantage of the significantly lower extinction in the NIR. The precise astrometry is obtained by taking many short-exposure images. Hence, the JASMINE Galactic Center survey data will be valuable for studies of exoplanet transits, asteroseismology, variable stars, and microlensing studies, including discovery of (intermediate-mass) black holes. We highlight a swath of such potential science, and also describe synergies with other missions.

ACO 1703 is a cluster recently found to have a variety of strongly lensed objects: there is a quintuply imaged system at z = 0.888 and several other lensed objects from z = 2.2 to 3.0 (the cluster itself is at z = 0.28). It is not difficult to model the lens, as previous work has already done. However, lens models are generically nonunique. We generate ensembles of models to explore the nonuniqueness. When the full range of source redshifts is included, all models are close to r [?] r -1 out to 200 kpc. But if the quint is omitted, both shallower and steeper models (e.g., r [?] r -2) are possible. The reason is that the redshift contrast between the quint and the other sources gives a good measurement of the enclosed mass at two different radii, thus providing a good estimate of the mass profile in between. This result supports universal profiles and explains why single-model approaches can give conflicting results. The mass map itself is elongated in the northwest-southeast direction, like the galaxy distribution. An overdensity in both mass and light is also apparent to the southeast, which suggests mesostructure.