The GLASS-JWST Early Release Science Programme: The NIRISS Spectroscopic Catalogue

We present a spectroscopic redshift catalogue of sources in the Abell 2744 cluster field, derived from JWST/NIRISS observations taken as part of the GLASS-JWST Early Release Science programme. We describe the data reduction, contamination modelling and source detection, as well as the data quality assessment, redshift determination and validation. The catalogue consists of 354 secure and 134 tentative redshifts, of which 245 are new spectroscopic redshifts, spanning a range $0.1 \leq z \leq 8.2$. These include 17 galaxies at the cluster redshift, one galaxy at $z \approx 8$, and a triply-imaged galaxy at $z = 2.653 \pm 0.002$. Comparing against galaxies with existing spectroscopic redshifts $z_{\rm{spec}}$, we find a small offset of $\Delta z = (z_{\rm{spec}} - z_{\rm{NIRISS}} )/(1 + z_{\rm{spec}} ) = (1.3 \pm 1.6) \times 10^{-3}$. We also present a forced extraction tool (pygrife) and a visualisation tool (pygcg) to the community, to aid with the reduction and classification of grism data. This catalogue will enable future studies of the spatially-resolved properties of galaxies throughout cosmic noon, including dust attenuation and star formation. As a first application of the catalogue, we discuss the spectroscopic confirmation of multiple image systems, and the identification of multiple overdensities at $1 < z < 2.7$.