Peter Rumler

Overview of the near-infrared spectrograph (NIRSpec) instrument on-board the James Webb Space Telescope (JWST)

The James Webb Space Telescope (JWST) mission is a collaborative project between the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA) and the Canadian Space Agency (CSA). JWST is considered the successor to the Hubble Space Telescope (HST) and although its design and science objectives are quite different, JWST is expected to yield equivalently astonishing breakthroughs in infrared space science. Due to be launched in 2013 from the French Guiana, the JWST observatory will be placed in an orbit around the anti- Sun Earth-Sun Lagrangian point, L2, by an Ariane 5 launcher, provided by ESA. The payload on board the JWST observatory consists of four main scientific instruments: a near-infrared camera (NIRCam), a combined mid-infrared camera/spectrograph (MIRI), a near-infrared tunable filter (TFI) and a nearinfrared spectrograph (NIRSpec). The instrument suite is completed by a Fine Guidance Sensor (FGS). Besides the provision of the Ariane 5 launcher, ESA, with EADS Astrium GmbH (D) as Prime Contractor, is fully responsible for the funding and the furnishing of NIRSpec and, at the same time, for approximately half of MIRI costs through special contributions from the ESA member states. NIRSpec is a multi-object, spectrograph capable of measuring the spectra of about 100 objects simultaneously at low (R=100), medium (R=1000), and high (R=2700) resolutions over the wavelength range between 0.6 micron and 5.0 micron. In this article we provide a general overview of its main design features and performances.

The JWST near-infrared spectrograph NIRSpec: status

The Near-Infrared Spectrograph NIRSpec is one of the four instruments of the James Webb Space Telescope (JWST). NIRSpec will cover the 0.6-5.0 micron range and will be capable of obtaining spectra of more than 100 objects simultaneously in its multi-object spectroscopy (MOS) mode. It also features a set of slits and an aperture for high contrast spectroscopy of individual sources, as well as an integral-field unit (IFU) for 3D spectroscopy. We will first show how these capabilities are linked to the four main JWST scientific themes. We will then give an overview of the NIRpec modes and spectral configurations with an emphasis on the layout of the field of view and of the spectra. Last, we will provide an update on the status of the instrument.

Status of the JWST/NIRSpec instrument

The Near-Infrared Spectrograph (NIRSpec) is one of the four instruments on the James Webb Space Telescope (JWST), scheduled for launch in 2018. NIRSpec has been designed and built by the European Space Agency (ESA) with Airbus Defense and Space Germany as prime contractor. The instrument covers the wavelength range from 0.6 to 5.3 micron and will be able to obtain spectra of more than 100 astronomical objects simultaneously by means of a configurable array of micro-shutters. It also features an integral field unit and a suite of slits for high contrast spectroscopy of individual objects. The extensive ground calibration campaign of NIRSpec was completed in Summer 2013, after which it was delivered to NASA for integration into the Integrated Science Instrument Module (ISIM). We highlight the major results from the instrument level calibration campaign which demonstrated full compliance with all opto-mechanical performance requirements. In addition, we present the current status of the instrument, describe the ongoing preparations for the Integrated Science Instrument Module (ISIM) test campaign to begin in June 2014, and briefly discuss plans for the pending exchange of the detector and micro-shutter assemblies following the first ISIM test cycle.

The Near Infrared Spectrograph (NIRSpec) on-ground calibration campaign

The Near Infrared Spectrograph (NIRSpec) is one of four science instruments aboard the James Webb Space Telescope (JWST) scheduled for launch in 2018. NIRSpec is sensitive in the wavelength range from ~0.6 to 5.0 micron and will be capable of obtaining spectra from more than a 100 objects simultaneously by means of a programmable micro shutter array. It will also provide an integral eld unit for 3D spectroscopy and xed slits for high contrast spectroscopy of individual sources and planet transit observations. We present results obtained during the rst cryogenic instrument testing in early 2011, demonstrating the excellent optical performance of the instrument. We also describe the planning of NIRSpecs forthcoming second calibration campaign scheduled for early 2013.

Status of the NIRSpec instrument

The Near Infrared Spectrograph (NIRSpec) is one of the four science instruments aboard the James Webb Space Telescope (JWST) scheduled for launch in 2014. NIRSpec is sensitive in the wavelength range from ~ 0.6 to 5.0 μm and will be capable of obtaining spectra of more than a 100 objects simultaneously, as well as fixed slit high contrast spectroscopy of individual sources. It also features an integral field unit for 3D spectroscopy. The key scientific objectives of the instrument include studies of star formation and chemical abundances of young distant galaxies and tracing the creation of the chemical elements back in time. In this paper, we present the status of the NIRSpec instrument as it is currently being prepared for its extensive ground calibration campaign later in 2010.

The JWST/NIRSpec instrument: update on status and performances

The Near-Infrared Spectrograph (NIRSpec) is one of the four instruments on the James Webb Space Telescope (JWST) which is scheduled for launch in 2018. NIRSpec is developed by the European Space Agency (ESA) with Airbus Defense and Space Germany as prime contractor. The instrument offers seven dispersers covering the wavelength range from 0.6 to 5.3 micron with resolutions from R ∼ 100 to R ∼ 2700. NIRSpec will be capable of obtaining spectra for more than 100 objects simultaneously using an array of micro-shutters. It also features an integral field unit with 3” x 3” field of view and a range of slits for high contrast spectroscopy of individual objects and time series observations of e.g. transiting exoplanets. NIRSpec is in its final flight configuration and underwent cryogenic performance testing at the Goddard Space Flight Center in Winter 2015/16 as part of the Integrated Science Instrument Module (ISIM). We present the current status of the instrument and also provide an update on NIRSpec performances based on results from the ISIM level test campaign.

Getting JWST’s NIRSpec back in shape

The James Webb Space Telescope (JWST) Observatory is the follow-on mission to the Hubble Space Telescope. JWST will be the biggest space telescope ever built and it will lead to astounding scientific breakthroughs. The mission will be launched in October 2018 from Kourou, French Guyana by an ESA provided Ariane 5 rocket. NIRSpec, one of the four instruments on board of the mission, recently underwent a major upgrade. New infrared detectors were installed and the Micro Shutter Assembly (MSA) was replaced as well. The rework was necessary because both systems were found to be degrading beyond a level that could be accepted. The techniques and procedures that were applied during this campaign will be elaborated in this paper. Some first cold test results of the upgraded instrument will be presented as well.

JWST's near infrared spectrograph status and performance overview

The James Webb Space Telescope (JWST) Observatory is the follow-on mission to the Hubble Space Telescope (HST). JWST will be the biggest space telescope ever built and it will lead to astounding scientific breakthroughs. The mission will be launched in October 2018 from Kourou, French Guyana by an ESA provided Ariane 5 rocket. NIRSpec, one of the four instruments on board of the mission, recently underwent a major upgrade. New infrared detectors were installed and the Micro Shutter Assembly (MSA) was replaced as well. The rework was necessary because both systems were found to be degrading beyond a level that could be accepted. Now in its final flight configuration, NIRSpec underwent a final cryogenic performance test at NASA’s Goddard Space Flight Center (GSFC) as part of the Integrated Science Instrument Module (ISIM). This paper will present a status overview and results of the recent test campaigns.

JWST’s near infrared spectrograph status and first OTIS test results

The James Webb Space Telescope (JWST) is frequently referred to as the follow-on mission to the Hubble Space Telescope (HST). The “Webb”, as it is often called, will be the biggest space telescope ever built and it will lead to astounding scientific breakthroughs. The observatory is currently scheduled for launch in 2020 from Kourou, French Guyana by an ESA provided Ariane 5 rocket. The Observatory houses four scientific instruments. One of them is NIRSpec, the multi-object Near Infrared Spectrograph, built for ESA by Airbus Defence and Space in Germany. After the JWST Optical telescope Element (OTE) integration and testing was completed in early 2016, the Integrated Science Instruments Module (ISIM) was integrated to the OTE in May 2016. The complete system of OTE and ISIM, now called OTIS, then successfully went through an acoustic and vibration test campaign at NASA Goddard Space Flight Center (GSFC). After this, the OTIS system was shipped to the Johnson Space Center (JSC) in Houston, TX, where a final 100+ days lasting cryogenic vacuum test was conducted inside the famous Thermal Chamber A. This paper presents NIRSpec’s hardware status and some preliminary test results from the OTIS test campaign.

Noise performance of the JWST/NIRSpec detector system

The Near-Infrared Spectrograph (NIRSpec) is one of the four science instruments onboard the James Webb Space Telescope (JWST). The instrument features a focal plane array (FPA) consisting of two 2048 × 2048 HAWAII-2RG sensor chip assemblies (SCAs) with a cutoff wavelength of approximately 5.3 μm. The detectors are read out via a pair of SIDECAR ASICs. To ensure a stable operating environment and best performance, the FPA is temperature controlled via a dedicated control loop by the NIRSpec focal plane electronics. The targeted in-orbit operating temperature of the NIRSpec FPA is close to 42.8 K. Due to the low background levels that the JWST will provide, most NIRSpec observations of very faint targets will be detector noise limited. Therefore, stringent noise requirements on the detector system were put in place. In order to meet these requirements, NIRSpec offers a dedicated readout mode for its detectors that is called improved reference sampling and subtraction (IRS2 ). In this paper we present the noise performance of the NIRSpec detectors as a function of readout mode and exposure parameters. We find that the NIRSpec detector system meets its stringent noise requirement of 6 electrons total noise in a ∼ 1000 second exposure. We also highlight the types and effects of different kinds of bad pixels that are present in the detectors in small numbers.