MISTY selects its targets primarily from DESI, which in its first data release spectroscopically identified approximately 350,000 dwarf galaxies to z ≤ 0.2, a number expected to grow to approximately 1,000,000 over the full DESI survey. We use the DESI dwarf-galaxy catalog (Manwadkar et al., submitted), which provides photometry, emission-line flux measurements, star-formation rates, stellar masses, and additional derived properties.

At the distances targeted by MISTY, DESI detects star-forming systems down to stellar masses of approximately 10⁶ M_☉and surface brightnesses brighter than μ_V ≈ 25 mag arcsec⁻², subject to emission-line detection limits. Our science goals require the detection of weak auroral lines in individual spaxels of the optical IFU data cubes, which imposes a minimum Hα flux on our targets.

Selection criteria

• Distance within 30 Mpc
• Stellar masses of 10⁶–10^8.5 M_☉
• Uniform sampling in the specific-star-formation-rate–metallicity plane
• The full range of large-scale environments: isolated dwarfs, overdense regions, satellites, and interacting systems
• DESI fiber Hα flux above 10⁻¹⁵ erg s⁻¹ cm⁻² for Magellan or 3 × 10⁻¹⁶ erg s⁻¹ cm⁻² for Keck
• Observable from Las Campanas or Maunakea

Sampling uniformly in the specific-star-formation-rate–metallicity plane, rather than reproducing the intrinsic distribution, ensures that MISTY covers the full diversity of the low-mass population, including the sparsely populated extremes of star-formation activity and metallicity.