Ultracool Dwarf Absolute Magnitude versus Spectral Type Relations for JWST NIRCam Filters

Abstract We synthesize JWST NIRCam photometry for a range of narrow, medium, and wide filters using SpeX prism spectra and parallaxes of 688 field-age and 151 young (≲200 Myr) ultracool dwarfs (spectral types M6–T9). We derive absolute magnitude-spectral type polynomial relations for the F164N, F187N, and F212N narrow filters; the F140M, F162M, F182M, and F210M medium filters; and the F115W, F150W, and F200W wide filters. Our relations enable the calculation of photometric distances for ultracool dwarfs observed with JWST in the absence of parallax measurements. Additionally, using the synthesized photometry to generate color–color figures can help distinguish high-redshift galaxies from brown dwarf interlopers.