Redshift & Wavelength Explorer

A typical star-forming galaxy, from the Lyman limit to 1 µm, stretched by cosmic expansion and viewed through Rubin, Roman, Euclid, UVEX and Habitable Worlds Observatory bandpasses. Built to show what upcoming large surveys like LSST will let us see that we can’t today — drag the slider and watch which filters catch the light.

z =0.00

Stretch factor (1 + z)

Light left this long ago

The 91 nm – 1 µm band arrives at

Lyα (121.6 nm) arrives at

Hα (656.3 nm) arrives at

Rest UV (91–300 nm) is in Rubin

Rest UV (91–300 nm) is in Roman

Rest UV (91–300 nm) is in Euclid

Rest UV (91–300 nm) is in UVEX

Rest UV (91–300 nm) is in HWO

Observed wavelength = rest wavelength × (1 + z). The axis is logarithmic, so redshifting slides the spectrum sideways without changing its shape. Violet shading marks where the rest-frame UV lands; dashed, faded filters sit entirely blueward of Lyα, so they see no flux from the galaxy (drop-outs). The spectrum is an illustrative model in arbitrary f_λ with exaggerated line widths and a simple intergalactic-medium absorption (Lyα forest and Lyman limit). Filter curves are smoothed top-hats built from approximate band edges, not the official throughput tables. UVEX shows its two imaging bands (FUV and NUV). HWO has no defined filter set yet, so its three bars are the notional UV, visible and near-infrared channels, with cutoffs that are still under discussion. Lookback time assumes flat ΛCDM, H₀ = 70, Ωm = 0.3.