  We synthesize JWST NIRCam photometry for the F164N, F187N, F212N narrow
filters, F140M, F162M, F182M, F210M medium filters, and F115W, F150W, F200W
wide filters, Euclid Near Infrared Spectrometer and Photometer (NISP)
photometry for the $Y_E J_E H_E$ filters, and Roman Wide Field Instrument (WFI)
photometry for the F106, F129, F146, F158, F184 and F213 filters using SpeX
prism spectra and parallaxes of 688 field-age and 151 young ($\lesssim$ 200
Myr) ultracool dwarfs (spectral types M6-T9). We derive absolute
magnitude-spectral type polynomial relations that enable the calculation of
photometric distances for ultracool dwarfs observed with JWST, and to be
observed with Euclid and Roman, 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 in
survey datasets. In particular, anticipating the upcoming Euclid Early Release
Observations, we provide synthetic Euclid colors for ultracool dwarfs in our
sample.
