We re-reduce and analyse the available James Webb Space Telescope (JWST) ERO and ERS NIRCam imaging (SMACS0723, GLASS, CEERS) in combination with the latest deep ground-based near-infrared imaging in the COSMOS field (provided by UltraVISTA DR5) to produce a new measurement of the evolving galaxy UV luminosity function (LF) over the redshift range 𝑧 = 8 − 15. This yields a new estimate of the evolution of UV luminosity density (𝜌 UV ), and hence cosmic star-formation rate density (𝜌 SFR ) out to within < 300 Myr of the Big Bang. Our results confirm that the high-redshift LF is best described by a double power-law (rather than a Schechter) function, and that the LF and the resulting derived 𝜌 UV (and thus 𝜌 SFR ), continues to decline gradually and steadily over this redshift range (as anticipated from previous studies which analysed the pre-existing data in a consistent manner). We provide details of the 55 high-redshift galaxy candidates, 44 of which are new, that have enabled this new analysis. Our sample contains 6 galaxies at 𝑧 ≥ 12, one of which appears to set a new redshift record as an apparently robust galaxy candidate at 𝑧 16.7, the properties of which we therefore consider in detail. The advances presented here emphasize the importance of achieving high dynamic range in studies of early galaxy evolution, and re-affirm the enormous potential of forthcoming larger JWST programmes to transform our understanding of the young Universe.

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