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We assemble a large comprehensive sample of 2534 z similar to 2, 3, 4, 5, 6, 7, 8, and 9 galaxies lensed by the six clusters from the Hubble Frontier Fields (HFF) program. 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 similar to 2-9 galaxies, finding sources as faint as -12.4 mag at z similar to 3 and -12.9 mag at z similar to 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). We also use the observed sigma(z) versus mu relations to derive constraints on the evolution of the luminosity function faint-end slope from z similar to 7 to z similar to 2, showing that faint-end slope results can be consistent with blank-field studies if, and only if, the selection efficiency shows no strong dependence on the magnification factor mu. This can only be the case if very low-luminosity galaxies are very small, being unresolved in deep lensing probes.

We assemble a large comprehensive sample of 2534 z similar to 2, 3, 4, 5, 6, 7, 8, and 9 galaxies lensed by the six clusters from the Hubble Frontier Fields (HFF) program. 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 similar to 2-9 galaxies, finding sources as faint as -12.4 mag at z similar to 3 and -12.9 mag at z similar to 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). We also use the observed sigma(z) versus mu relations to derive constraints on the evolution of the luminosity function faint-end slope from z similar to 7 to z similar to 2, showing that faint-end slope results can be consistent with blank-field studies if, and only if, the selection efficiency shows no strong dependence on the magnification factor mu. This can only be the case if very low-luminosity galaxies are very small, being unresolved in deep lensing probes.

We present the deepest Spitzer/InfraRed Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 mu m wide-area mosaics yet over the Great Observatories Origins Deep Survey (GOODS)-N and GOODS-S fields as part of the GOODS Reionization Era wide-Area Treasury from Spitzer (GREATS) project. We reduced and mosaicked in a self-consistent way observations taken by the 11 different Spitzer/IRAC programs over the two GOODS fields from 12 yr of Spitzer cryogenic and warm-mission data. The cumulative depth in the 3.6 mu m and 4.5 mu m bands amounts to similar to 4260 hr, similar to 1220 hr of which are new very deep observations from the GREATS program itself. In the deepest area, the full-depth mosaics reach greater than or similar to 200 hr over an area of similar to 100 arcmin(2), corresponding to a sensitivity of similar to 29 AB magnitude at 3.6 mu m (1 sigma for point sources). Archival cryogenic 5.8 mu m and 8.0 mu m band data (a cumulative 976 hr) are also included in the release. The mosaics are projected onto the tangential plane of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS at a 0.'' 3 pixel(-1) scale. This paper describes the methodology enabling, and the characteristics of, the public release of the mosaic science images, the corresponding coverage maps in the four IRAC bands, and the empirical point-spread functions (PSFs). These PSFs enable mitigation of the source blending effects by taking into account the complex position-dependent variation in the IRAC images. The GREATS data products are in the Infrared Science Archive. We also release the deblended 3.6-8.0 mu m photometry 9192 Lyman-break galaxies at z similar to 3.5-10. GREATS will be the deepest mid-infrared imaging until the James Webb Space Telescope and, as such, constitutes a major resource for characterizing early galaxy assembly.