Lensed Cepheids in the Spock arc at z = 1.0054. The plot shows ten magnification realizations of the 70 luminous Cepheid stars in the LMC (Riess et al. 2019) but placed at the redshift of the Spock arc and magnified by the galaxy cluster plus microlenses. The J-band redshifts to 2.5 μm, i.e., between JWST’s F200W and F277W bands. One Cepheid from this sample is expected to be observed in observations reaching depth F200W ∼ 29.5 AB amg.