z~2-10 galaxies magnified by HFF clusters. I.

Making use of the availability of multiple independent magnification models for each of the HFF clusters and alternatively treating one of the models as the "truth," we show that the median magnification factors from the v4 parametric models are typically reliable to values of 30-50, and in one case to 100.

Using the median magnification factor from the latest v4 models, we estimate the UV luminosities of the 2534 lensed z~2-9 galaxies, finding sources as faint as -12.4mag at z~3 and -12.9mag at z~7. We explicitly demonstrate the power of the surface density-magnification relations {Sigma}(z) versus {mu} in the HFF clusters to constrain both distant galaxy properties and cluster lensing properties. Based on the {Sigma}(z) versus {mu} relations, we show that the median magnification estimates from existing public models must be reliable predictors of the true magnification {mu} to {mu}<15 (95% confidence).