JADES Dark Horse: demonstrating high-multiplex observations with JWST /NIRSpec dense-shutter spectroscopy in the JADES Origins Field

D’Eugenio, Francesco, Nelson, Erica J, Eisenstein, Daniel J, Maiolino, Roberto, Carniani, Stefano, Scholtz, Jan, Curti, Mirko, Willmer, Christopher N A, Bunker, Andrew J, Helton, Jakob M, Juodžbalis, Ignas, Sun, Fengwu, Tacchella, Sandro, Arribas, Santiago, Cameron, Alex J, Charlot, Stéphane, Curtis-Lake, Emma, Hainline, Kevin, Johnson, Benjamin D, Robertson, Brant, Williams, Christina C, Willott, Chris, Baker, William M, Chevallard, Jacopo, Danhaive, A Lola, Isobe, Yuki, Ji, Xihan, Ji, Zhiyuan, Jones, Gareth C, Kumari, Nimisha, Looser, Tobias J, Lyu, Jianwei, Parlanti, Eleonora, Perna, Michele, Puskás, Dávid, Rinaldi, Pierluigi, Simmonds, Charlotte, Sun, Yang, Übler, Hannah, Venturi, Giacomo, Witstok, Joris, Wu, Zihao and Zhu, Yongda (2026) JADES Dark Horse: demonstrating high-multiplex observations with JWST /NIRSpec dense-shutter spectroscopy in the JADES Origins Field. Monthly Notices of the Royal Astronomical Society, 549 (2). ISSN 0035-8711

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We present James Web Space Telescope/NIRSpec dense-shutter spectroscopy (DSS). This novel observing strategy with the NIRSpec/multi-shutter assembly (MSA) deliberately permits a high number of controlled spectral overlaps to reach extreme multiplex while retaining the low background of slit spectroscopy. In a single configuration over the JADES Origins Field, we opened shutters on all faint ( mag) candidates, prioritizing emission-line science and rejecting only bright continuum sources. Using 33.6 and 35.8 ks on-source in G235M and G395M, we observed a single mask with 850 sources, obtaining spectroscopic redshifts for 540 galaxies over . The per-configuration target density in DSS mode is 4–5 higher than standard no- and low-overlap MSA strategies (

Item Type	Article
Identification Number	10.1093/mnras/stag824
Additional information	© The Author(s) 2026. Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/)
Keywords	methods: observational, galaxies: ism, techniques: spectroscopic, surveys, instrumentation: spectrographs, galaxies: high-redshift
Date Deposited	01 Jun 2026 09:23
Last Modified	02 Jun 2026 04:45