MOCSS: Multi-Object Coronagraphy for JWST/NIRSpec Slitless Spectroscopy
Abstract
We present an experimental JWST/NIRSpec observational method to obtain R≳1000 G140M/F100LP slitless spectroscopic observations. This "Multi-Object Coronagraphy for Slitless Spectroscopy" (MOCSS) technique involves opening essentially all microshutters on NIRSpec simultaneously while closing shutters corresponding on-sky with known bright objects. Through observations of the Hubble Ultra Deep Field, we demonstrate the discovery potential of these deep, high resolution observations without the need for target pre-selection. We obtain a catalog of 22 secure multi-line emitters at 1.3<z<4.6, with observations of [OII], [OIII], Hα, Hβ and [NII] lines, accounting for ∼80% of the emission lines identified directly in the dispersed images. The MOCSS survey provides first time spectroscopic redshifts for 18 of these sources. We also demonstrate that first order traces of the NIRSpec/G140M/F100LP observing mode extend substantially beyond the nominal ∼1.89μm red cutoff, as far as 2.94μm in the most extreme case. Compared to existing NIRISS WFSS of similar exposure times, we find that the MOCSS technique can observe very faint lines while covering the full 1−2 μm regime without gaps in wavelength coverage. This study describes the highest-resolution slitless spectroscopy campaign of the 1−2 μm regime and emphasizes the discovery potential of this unorthodox observational technique.
Related
- A Single Line-Emitter Identified in an Unbiased Search with JWST/NIRSpec: Multi-Object Coronagraphy for Slitless Spectroscopy
- An Archival Calibration of JWST/MIRI Prism Wide-Field Slitless Spectroscopy: Methodology, Performance, and a Mid-Infrared Spectral Atlas of Galaxies at z=0−4 in the GOODS-N/S Fields
- Surveying the Universe in 4D: Beating Cosmic Variance with Wide-Field Slitless Spectroscopy from HST, JWST, Euclid, Roman, and Beyond
- Cosmic Noon Galaxies in the Hubble Ultra Deep Field with MIRI Wide-Field Slitless Spectroscopy
- Source--Line Associations in JWST/NIRSpec Dense-Shutter Spectroscopy
BibTeX
@misc{huberty2026mocss,
title = {{MOCSS: Multi-Object Coronagraphy for JWST/NIRSpec Slitless Spectroscopy}},
author = {Mason S. Huberty and Claudia Scarlata and Matthew J. Hayes and Alaina Henry and Danielle A. Berg and Vieri Cammelli and Richard Ellis and Anne E. Jaskot and Matilde Mingozzi and Pierluigi Monaco and Alberto Saldana-Lopez and Jonathan C. Tan and Alice Young},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.36003},
eprint = {2609.36003},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.36003},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - MOCSS: Multi-Object Coronagraphy for JWST/NIRSpec Slitless Spectroscopy
AU - Mason S. Huberty
AU - Claudia Scarlata
AU - Matthew J. Hayes
AU - Alaina Henry
AU - Danielle A. Berg
AU - Vieri Cammelli
AU - Richard Ellis
AU - Anne E. Jaskot
AU - Matilde Mingozzi
AU - Pierluigi Monaco
AU - Alberto Saldana-Lopez
AU - Jonathan C. Tan
AU - Alice Young
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.36003
UR - https://arxiv.org/abs/2609.36003
AB - We present an experimental JWST/NIRSpec observational method to obtain R≳1000 G140M/F100LP slitless spectroscopic observations. This "Multi-Object Coronagraphy for Slitless Spectroscopy" (MOCSS) technique involves opening essentially all microshutters on NIRSpec simultaneously while closing shutters corresponding on-sky with known bright objects. Through observations of the Hubble Ultra Deep Field, we demonstrate the discovery potential of these deep, high resolution observations without the need for target pre-selection. We obtain a catalog of 22 secure multi-line emitters at 1.3<z<4.6, with observations of [OII], [OIII], Hα, Hβ and [NII] lines, accounting for ∼80% of the emission lines identified directly in the dispersed images. The MOCSS survey provides first time spectroscopic redshifts for 18 of these sources. We also demonstrate that first order traces of the NIRSpec/G140M/F100LP observing mode extend substantially beyond the nominal ∼1.89μm red cutoff, as far as 2.94μm in the most extreme case. Compared to existing NIRISS WFSS of similar exposure times, we find that the MOCSS technique can observe very faint lines while covering the full 1−2 μm regime without gaps in wavelength coverage. This study describes the highest-resolution slitless spectroscopy campaign of the 1−2 μm regime and emphasizes the discovery potential of this unorthodox observational technique.
ER -