The GLASS-JWST early release science programme

We present a spectroscopic redshift catalogue of sources within the Abell 2744 cluster field, derived from JWST/NIRISS observations, obtained as part of the GLASS-JWST Early Release Science programme. We describe the data reduction, the contamination modelling, and the source detection, as well as the data quality assessment, the redshift determination, and the validation. The catalogue consists of 354 secure and 134 tentative redshifts, of which 245 are new spectroscopic redshifts, spanning the range 0.1≤z≤8.2. These include 17 galaxies at the cluster redshift, one galaxy at z≈8, and a triply imaged galaxy at z = 2.653±0.002. Comparing against galaxies with existing spectroscopic redshifts (zspec), we find a small offset of Δz=(zspec‑zNIRISS)/(1+zspec) =(1.3±1.6)×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.