In-orbit Performance of the Near-infrared Spectrograph NIRSpec on the James Webb Space Telescope

The Near-Infrared Spectrograph (NIRSpec) is one of the four focal plane instruments on the James Webb Space Telescope. In this paper, we summarize the in-orbit performance of NIRSpec, as derived from data collected during its commissioning campaign and the first few months of nominal science operations. More specifically, we discuss the performance of some critical hardware components such as the two NIRSpec Hawaii-2RG detectors, wheel mechanisms, and the microshutter array. We also summarize the accuracy of the two target acquisition procedures used to accurately place science targets into the slit apertures, discuss the current status of the spectrophotometric and wavelength calibration of NIRSpec spectra, and provide the “as measured” sensitivity in all NIRSpec science modes. Finally, we point out a few important considerations for the preparation of NIRSpec science programs.

[1]  D. Eisenstein,et al.  Performance of NIRCam on JWST in Flight , 2023, Publications of the Astronomical Society of the Pacific.

[2]  C. Keyes,et al.  Spectroscopic Time-series Performance of JWST/NIRSpec from Commissioning Observations , 2022, Publications of the Astronomical Society of the Pacific.

[3]  Thomas P. Zielinski,et al.  Commissioning the James Webb Space Telescope optical telescope element , 2022, Astronomical Telescopes + Instrumentation.

[4]  P. Ferruit,et al.  The in-flight noise performance of the JWST/NIRSpec detector system , 2022, Astronomical Telescopes + Instrumentation.

[5]  P. Ferruit,et al.  Astrometric and wavelength calibration of the NIRSpec instrument during commissioning using a model-based approach , 2022, Astronomical Telescopes + Instrumentation.

[6]  P. Ferruit,et al.  In-flight performance and calibration of the grating wheel assembly sensors (NIRSpec/JWST) , 2022, Astronomical Telescopes + Instrumentation.

[7]  P. Ferruit,et al.  Optical throughput and sensitivity of JWST NIRSpec , 2022, Astronomical Telescopes + Instrumentation.

[8]  C. Keyes,et al.  In-flight performance of the NIRSpec micro shutter array , 2022, Astronomical Telescopes + Instrumentation.

[9]  C. Keyes,et al.  In-orbit commissioning of the near-infrared spectrograph on the James Webb Space Telescope , 2022, Astronomical Telescopes + Instrumentation.

[10]  H. Rix,et al.  The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope. IV. Capabilities and predicted performance for exoplanet characterization , 2022, Astronomy & Astrophysics.

[11]  H. Rix,et al.  The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope. II. Multi-object spectroscopy (MOS) , 2022, Astronomy & Astrophysics.

[12]  H. Rix,et al.  The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope. I. Overview of the instrument and its capabilities , 2022, Astronomy & Astrophysics.

[13]  H. Rix,et al.  The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope. III. Integral-field spectroscopy , 2022, Astronomy & Astrophysics.

[14]  J. Leisenring,et al.  JWST Noise Floor. I. Random Error Sources in JWST NIRCam Time Series , 2020, The Astronomical Journal.

[15]  M. Robberto,et al.  The Impact of Cosmic Rays on the Sensitivity of JWST/NIRSpec , 2019, Publications of the Astronomical Society of the Pacific.

[16]  Marco Sirianni,et al.  Target acquisition for multi-object spectroscopy with JWST NIRSpec , 2018, Astronomical Telescopes + Instrumentation.

[17]  Markus Loose,et al.  Improved Reference Sampling and Subtraction: A Technique for Reducing the Read Noise of Near-infrared Detector Systems , 2017, 1707.09387.

[18]  G. de Marchi,et al.  Flat-fielding strategy for the JWST/NIRSpec multi-object spectrograph , 2016, Astronomical Telescopes + Instrumentation.

[19]  Marco Sirianni,et al.  A model-based approach to the spatial and spectral calibration of NIRSpec onboard JWST , 2016, 1606.05640.

[20]  Matthew A. Greenhouse,et al.  New and Better Detectors for the JWST Near-Infrared Spectrograph , 2014 .

[21]  Ralph C. Bohlin,et al.  Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared , 2014, 1406.1707.

[22]  Stephan M. Birkmann,et al.  The accuracy of the NIRSpec grating wheel position sensors , 2012, Other Conferences.

[23]  Wolfgang Holota,et al.  Opto-mechanical design of the near infrared spectrograph NIRSpec , 2005, SPIE Optics + Photonics.

[24]  Shane Jacobson,et al.  Detectors for the James Webb Space Telescope Near‐Infrared Spectrograph. I. Readout Mode, Noise Model, and Calibration Considerations , 2007, SPIE Astronomical Telescopes + Instrumentation.