Full data release of the Cycle 2 program GO-3073 (PI: M. Castellano; data reduction and analysis: L. Napolitano).
The GO-3073 NIRSpec program has observed the GLASS-JWST field (Treu et al. 2022) with two partially overlapping pointings, observed on 2023 Oct. 24, and on 2024 July 3-4, respectively. Each pointing is divided into three visits of exposure time of 6567 s each, adopting a NRSIRS2 readout pattern, standard 3-shutter “slits”, and a 3-point nodding. The main targets of the program were the z=12 candidate GHZ2 from Castellano et al. 2022 and the five colour-selected z~10 candidates within the GLASS-JWST ERS region discussed in Castellano et al. 2023. Additional colour-selected candidates and objects with photometric redshift z > 9 were included as high-priority fillers. The allocation of the remaining slitlets was maximised with the MSA planning tool to target sources from the Paris et al. 2023 and Merlin et al. 2024 catalogues, assigning a higher priority to objects with photometric redshift z>5. A total of 979 targets, including serendipitously observed sources have been extracted.
The redshift measurements have been performed independently by three team members visually inspecting 1D and 2D spectra and manually matching the spectral position of emission and absorption features. The reliability of the redshift measurements was evaluated using the same flagging convention as for previous surveys such as VVDS, zCOSMOS and VANDELS, as described in the data release README file. We find 407 objects with Flag>=3, i.e. highly reliable confirmed measurements, and 196 tentative redshifts with Flag=1 or 2.
A detailed description of the data reduction is presented in Castellano et al. 2025. The dataset can be downloaded at the following links:
Download the 1D and 2D reduced NIRSpec spectra.
Download the redshift measurements table.
(Note: the data will be made publicly available after paper review, for any request please contact us).
If you use these data for your science please cite Castellano et al. 2025 (find below other team publications to be considered when relevant). If you find any issue or need assistance, please contact marco.castellano [at] inaf.it and lorenzo.napolitano [at] inaf.it.
Publications by the team:
JWST Spectroscopic Insights Into the Diversity of Galaxies in the First 500 Myr: Short-Lived Snapshots Along a Common Evolutionary Pathway – Roberts-Borsani et al., 2025, MNRAS, subm.
The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-Ray Source at z = 10.145 – Napolitano et al. 2025, ApJ, 989, 75
Seven wonders of Cosmic Dawn: JWST confirms a high abundance of galaxies and AGN at z ≃ 9–11 in the GLASS field – Napolitano et al. 2025 A&A, 693A, 50
Not just PAH3.3: Why galaxies turn red in the near-infrared – Vulcani et al. 2025 A&A, 693A, 204
Accelerated Emergence of Evolved Galaxies in Early Overdensities at z ∼ 5.7 – Morishita et al., 2025, ApJ, 982, 153
The ionizing photon production efficiency of star-forming galaxies at z ∼ 4–10 – Llerena et al., 2025, A&A, 698A, 302
Between the Extremes: A JWST Spectroscopic Benchmark for High-redshift Galaxies Using ∼500 Confirmed Sources at z ≥ 5 – Roberts-Borsani et al., 2024, ApJ, 976, 193
Evidence of Extreme Ionization Conditions and Low Metallicity in GHZ2/GLASS-Z12 from a Combined Analysis of NIRSpec and MIRI Observations – Calabro’ et al., 2024, ApJ, 975, 245
JWST NIRSpec Spectroscopy of the Remarkable Bright Galaxy GHZ2/GLASS-z12 at Redshift 12.34 – Castellano et al., 2024, ApJ, 972, 143