CEERS Simulated Data Release v2

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Coming soon: NIRCam Wide Field Slitless Spectroscopy

Simulated NIRSpec MSA Spectroscopy for CEERS Pointing 3

We have simulated NIRSpec MSA data for CEERS pointing 3 using the NIRSpec Instrument Performance Simulator (IPS; Piquéras et al. 2010), with input sources taken from the CANDELS EGS photometric catalog (Stefanon et al. 2017). The input spectra are simulated as continuum SED models with emission lines using the MAPPINGS library (Allen et al. 2008), with simulation scenes created from the CEERS MSA configurations. The IPS turns these scenes into simulated count-rate maps, which are the input for Stage 2 of the JWST Calibration Pipeline.

To access the full data release directly, visit this link. Please see the associated README describing the release.

Alternatively, see below to access the fully reduced 2D spectra and flux calibrated 1D spectra. We also provide the count-rate maps and step-by-step instructions for reducing them through Stages 2 and 3 of the pipeline.


  • Instrument: NIRSpec
  • Mode: Multi-Object Spectroscopy with the Micro-Shutter Assembly (MSA)
  • Source of Simulations: NIRSpec Instrument Performance Simulator (IPS)
  • Calibration Pipeline Used: jwst v1.4.2
  • APT (version 2021.2): CEERS ERS 1345
  • Target: CEERS Pointing 3
  • Filters/gratings: G140M/F100LP, G235M/F170LP, G395M/F290LP, Prism/Clear
  • Readout: NRSIRS2
  • Observation specification: 13 groups, 1 integration
  • Dithers: 3-shutter slitlet nod pattern

Calibrated 1D and 2D spectra

  • Fully reduced 2D and 1D spectra in all 4 grating/filter pairs are available here or in the table below.
  • Please see the README for information on the calibration and file structures.
  • For each grating/filter in the table below we provide three zipped directories of output spectra:
    • Distortion-corrected calibrated 2D spectra (*_s2d.fits)
    • Calibrated 1D spectra (*_x1d.fits), which are extracted from the 2D spectra *_s2d.fits files
    • Flux calibrated 1D spectra (*_fluxcal_1D_spec.dat), applying our custom flux calibration procedure

Data reduction

Reducing the count-rate maps through the JWST Calibration Pipeline requires a considerable amount of time and memory. We therefore provide instructions on how to reduce the simulated data in two parts:

CEERS3 NIRSpec MSA Detailed Reduction (Part 1, recommended starting place):

Part 1 incluces all input files necessary to reduce exposures for one prism observation and one G395M observation, including a notebook (CEERS_NIRSpec_MSA_detailed_reduction.ipynb) that demonstrates running the Calibration Pipeline steps as well as custom processing steps we've developed for the simulated data.

Download CEERS3_NIRSpec_MSA_detailed_reduction.zip (~400 MB). Note: unzips to 1.7 GB and takes up ~6 GB including all reference files and calibration pipeline outputs, i.e., after running all steps in the notebook.

CEERS3 Full NIRSpec Reduction (Part 2):

Part 2 provides the full reduction of the complete pointing 3, with steps provided in the Jupyter notebook CEERS3_full_NIRSpec_reduction.ipynb.

Download CEERS3_full_NIRSpec_reduction.zip (~3 GB). Note: unzips to ~4.6 GB and takes up ~12.5 GB after performing all steps.

Please consult the README files packaged with each zipped directory before performing any of the reduction steps.