(a) and (b) JWST/NIRSpec Prism spectral standards for M, L, and T dwarfs (a) and subdwarfs (b), plotted in f_ν flux density units (black lines). Spectra are normalized in the 1–2 μm region and offset by constants. Spectral types based on the best-match NIR standards (overplotted color lines) are listed along the left side. (c) Comparison of spectral indices H₂O–H and K/H for ground-based spectral standards (colored symbols) and JWST/NIRSpec Prism spectra (black dots). Selected NIRSpec standards are encircled and labeled. For the NIR standards, symbol colors indicate spectral class (M dwarf = green, L dwarf = blue, T dwarf = magenta), while symbol shapes indicate metallicity class (dwarf = squares, d/sd = inverted triangle, sd = triangles). (d) JWST/NIRSpec Prism spectra of our L1 (solid blue line) and d/sdL1 (dashed blue line) standards, compared to the NIR sdL1 standard (faded blue line; A. J. Burgasser et al. 2025) over 0.9–3.0 μm. Shaded bands indicate the regions sampled for the H₂O–H (H₂O over H-band) and K/H (K-band over H-band) indices.

(The data used to create this figure are available in the online article.)

(The data used to create this figure are available.)