Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph

Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph (FGS-NIRISS) is an instrument on the James Webb Space Telescope (JWST) that combines a Fine Guidance Sensor and a science instrument, a near-infrared imager and a spectrograph.{{cite web

|url=http://jwst.nasa.gov/fgs.html |title=The James Webb Space Telescope

|work=National Aeronautics and Space Administration |accessdate=November 27, 2016 |url-status=live |archiveurl=https://web.archive.org/web/20211214020454/https://jwst.nasa.gov/content/observatory/instruments/fgs.html |archivedate=December 14, 2021}} The FGS/NIRISS was designed by the Canadian Space Agency (CSA) and built by Honeywell{{Cite web |date=18 February 2011 |title=Canada's role in Webb |url=https://www.asc-csa.gc.ca/eng/satellites/jwst/canada-role.asp |url-status=live |archive-url=https://web.archive.org/web/20240116005355/https://www.asc-csa.gc.ca/eng/satellites/jwst/canada-role.asp |archive-date=16 January 2024 |access-date=7 March 2022 |publisher=Canadian Space Agency }} as part of an international project to build a large infrared space telescope with the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). FGS-NIRISS observes light from the wavelengths of 0.8 to 5.0 microns. The instrument has four different observing modes.{{Cite conference |editor1-first=Mark C |editor1-last=Clampin |editor2-last=Fazio |editor2-first=Giovanni G |editor3-last=MacEwen |editor3-first=Howard A |editor4-last=Oschmann |editor4-first=Jacobus M |last1=Doyon |first1=René |last2=Hutchings |first2=John B. |last3=Beaulieu |first3=Mathilde |last4=Albert |first4=Loic |last5=Lafrenière |first5=David |last6=Willott |first6=Chris |last7=Touahri |first7=Driss |last8=Rowlands |first8=Neil |last9=Maszkiewicz |first9=Micheal |first10=Alex W. |last10=Fullerton |first11=Kevin |last11=Volk |last12=Martel |first12=André R. |last13=Chayer |first13=Pierre |first14=Anand |last14=Sivaramakrishnan |last15=Abraham |first15=Roberto |last16=Ferrarese |first16=Laura |last17=Jayawardhana |first17=Ray |first18=Doug |last18=Johnstone |last19=Meyer |first19=Michael |last20=Pipher |first20=Judith L. |last21=Sawicki |first21=Marcin |date=22 August 2012 |title=The JWST Fine Guidance Sensor (FGS) and Near-Infrared Imager and Slitless Spectrograph (NIRISS) |url=http://spie.org/Publications/Proceedings/Paper/10.1117/12.926578 |conference=Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave |publisher=SPIE |volume=8442 |pages=84422R |bibcode=2012SPIE.8442E..2RD |doi=10.1117/12.926578 |s2cid=120702854 |url-access=subscription }}

Physically the FGS and NIRISS are combined, but optically they are separate with the FGS being used by the telescope to point it, whereas NIRISS is an independent science instrument.{{Cite web|url=http://hubblesite.org/webb_telescope/technology_at_the_extremes/webb_instruments.php#fgs-niriss|title=Webb's Instruments}} The spectroscopic mode is capable of doing exoplanet spectroscopy.{{Cite web |title=ESA Science & Technology: The JWST instrument suite |url=https://sci.esa.int/web/jwst/-/45752-jwst-instruments |url-status=live |archive-url=https://web.archive.org/web/20231227000503/https://sci.esa.int/web/jwst/-/45752-jwst-instruments |archive-date=27 December 2023 |access-date=27 November 2016 |website=sci.esa.int |publisher=ESA }} The detector for NIRISS is a 2048 × 2048 pixel mercury cadmium telluride (HgCdTe) array, where each pixel is 18 microns on a side according to the STSCi.{{cite web|url=http://www.stsci.edu/jwst/instruments/niriss/instrumentdesign|archive-url=https://wayback.archive-it.org/all/20140203181439/http://www.stsci.edu/jwst/instruments/niriss/instrumentdesign|url-status=dead|archive-date=February 3, 2014|publisher=stsci.edu|title=NIRISS: Near-InfraRed Imager and Slitless Spectrograph|access-date=2016-11-27}} The field of view is 2.2' × 2.2' which gives a plate scale of about 0.065 arcsec/pixel.

The FGS will help the telescope aim and stay pointed at whatever it is commanded to look at.{{cite web|url=http://www.asc-csa.gc.ca/eng/satellites/jwst/contribution.asp|publisher=asc-csa.gc.ca|title=Canada's Contribution to the James Webb Space Telescope – Canadian Space Agency|access-date=2016-11-27|archive-date=2016-11-27|archive-url=https://web.archive.org/web/20161127024555/http://www.asc-csa.gc.ca/eng/satellites/jwst/contribution.asp|url-status=dead}} FGS helps provide data to the JWST Attitude Control System (ACS) and to do this it has a big sky coverage and sensitivity, to give a high probability it can find a guide star.{{Cite web |title=FGS – Fine Guidance Sensor |url=http://www.stsci.edu/jwst/instruments/fgs |url-status=dead |archive-url=https://web.archive.org/web/20161211155015/http://www.stsci.edu/jwst/instruments/fgs |archive-date=11 December 2016 |access-date=27 November 2016 |website=stsci.edu |publisher=Space Telescope Science Institute }}

NIRISS is designed for performing:{{cite web |title=JWST Near Infrared Imager and Slitless Spectrograph - JWST User Documentation |url=https://jwst-docs.stsci.edu/jwst-near-infrared-imager-and-slitless-spectrograph |website=jwst-docs.stsci.edu |access-date=14 March 2022}}{{Cite web |title=JWST Pocket Guide January 2022 |url=https://www.stsci.edu/files/live/sites/www/files/home/jwst/instrumentation/_documents/jwst-pocket-guide.pdf |url-status=live |archive-url=https://web.archive.org/web/20230610222700/https://www.stsci.edu/files/live/sites/www/files/home/jwst/instrumentation/_documents/jwst-pocket-guide.pdf |archive-date=10 June 2023 |access-date=14 March 2022 |website=stsci.edu |publisher=Space Telescope Science Institute }}

Near-infrared imaging
Wide-field slitless spectroscopy
Single object slitless spectroscopy
Aperture masking interferometry

The aperture masking interferometry mode uses a seven-hole aperture masking disc, and should allow the detection of exoplanets within certain ranges of light and types of stars.

The Engineering Test Unit of the FGS was delivered to NASA in 2010.{{Cite press release |last1=Chandler |first1=Lynn |last2=Chicone |first2=Ruth Ann |date=8 September 2010 |title=NASA Goddard Receives the Webb Telescope's Guiding Light from Canada |url=https://www.nasa.gov/topics/technology/features/fgs-testing.html |url-status=dead |archive-url=https://web.archive.org/web/20101222140638/https://www.nasa.gov/topics/technology/features/fgs-testing.html |archive-date=22 December 2010 |publisher=NASA & CSA |id=Goddard 10-077 }} The flight units were planned to be delivered later after the ETU, which enabled testing with other JWST hardware. The flight units of FGS/NIRISS were delivered to NASA in August 2012.{{Cite web |last=Gutro |first=Rob |date=13 August 2012 |title=Second Flight Instrument Delivered for James Webb Space Telescope |url=https://www.nasa.gov/topics/technology/features/2nd-webb-inst.html |url-status=dead |archive-url=https://web.archive.org/web/20120815192505/https://www.nasa.gov/topics/technology/features/2nd-webb-inst.html |archive-date=15 August 2012 |website=www.nasa.gov |publisher=NASA }}

Commissioning is complete as of the following dates:

Single object slitless spectroscopy, 06/22/2022
Wide field slitless spectroscopy, 06/14/2022
Aperture masking interferometry, 06/14/2022
Imaging (parallel only), 06/08/2022

FGS

File:Webb’s Fine Guidance Sensor Provides a Serendipitous Preview.jpg

The FGS functionality supports JWST pointing at the desired targets. The FGS is designed to find pre-selected guide stars, which allows the telescope to stay precisely pointed at the desired target.{{Cite web |title=JWST Fine Guidance Sensor - JWST User Documentation |url=https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-fine-guidance-sensor |url-status=live |archive-url=https://web.archive.org/web/20230929164749/https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-fine-guidance-sensor |archive-date=29 September 2023 |access-date=14 March 2022 |website=jwst-docs.stsci.edu |publisher=Space Telescope Science Institute }} The actual pointing of the telescope is handled by other segments, especially the systems in the spacecraft bus and the fine guidance mirror in the Optical Telescope Element.

Unlike the Hubble Space Telescope's field guidance sensors, which can be used in astrometry such as studying exoplanets, the James Webb Space Telescope's field guidance sensors are not available for science proposals by researchers because they are used exclusively for guiding and calibration.https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-fine-guidance-sensor#gsc.tab=0 . Retrieved 15 March 2025.https://esahubble.org/about/general/instruments/fgs/ . Retrieved 15 March 2025.

Tuneable filter (cancelled)

Previously, CSA was working on a tuneable image filter.{{Cite conference |last=Sabelhaus |first=Phillip A. |date=1 June 2004 |title=An Overview of the James Webb Space Telescope (JWST) Project |url=https://ntrs.nasa.gov/citations/20040171280 |conference=SPIE |publisher=NASA |id=SPIE-5487-21 |archive-url=https://web.archive.org/web/20240124142942/https://ntrs.nasa.gov/citations/20040171280 |archive-date=24 January 2024 |via=ntrs.nasa.gov |url-status=live }} This device was intended to allow a narrow filter band to be selected (as opposed to a fixed filter band). The TFI was cancelled in 2011 and the work rolled-over into the NIRISS.{{Cite web |title=Tunable Filter Imager (TFI) |url=http://www.stsci.edu/jwst/instruments/tfi/ |url-status=dead |archive-url=https://web.archive.org/web/20100604103119/http://www.stsci.edu/jwst/instruments/tfi/ |archive-date=4 June 2010 |publisher=Space Telescope Science Institute }} The TFI would have a selectable filter band between 1.5–5 μm.{{cite book |last1=Doyon |first1=R. |last2=Hutchings |first2=J. |last3=Rowlands |first3=N. |last4=Evans |first4=C. E. |last5=Greenberg |first5=E. |last6=Haley |first6=C. |last7=Scott |first7=A. D. |last8=Touahri |first8=D. |last9=Beaulieu |first9=M. |last10=Lafrenière |first10=D. |last11=Abraham |first11=R. |last12=Barton |first12=E. |last13=Chayer |first13=P. |last14=Ferrarese |first14=L. |last15=Fullerton |first15=A. W. |last16=Jayawardhana |first16=R. |last17=Johnstone |first17=D. |last18=Martel |first18=A. |last19=Meyer |first19=A. W. M. R. |last20=Pipher |first20=J. |last21=Saad |first21=K. |last22=Sawicki |first22=M. |last23=Sivaramakrishnan |first23=A. |last24=Volk |first24=K. |editor-first1=Jacobus M |editor-first2=Mark C |editor-first3=Howard A |editor-last1=Oschmann, Jr |editor-last2=Clampin |editor-last3=MacEwen |title=Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave |chapter=The JWST tunable filter imager (TFI) |date=16 July 2010 |volume=7731 |pages=77310F |doi=10.1117/12.857382 |s2cid=122033089 |chapter-url=https://www.researchgate.net/publication/259677074 |access-date=14 March 2022}}

{{blockquote|In July 2011 the Canadian Space Agency reluctantly discontinued work on the Tunable Filter Imager (TFI) when it became clear that issues associated with the cryogenic operation of its Fabry-Perot etalon were unlikely to be resolved in time to meet the instrument's delivery schedule... | STSCI}}

A developmental version of the TFI was tested in Ontario, Canada in 2010. The chief problem was the time needed to resolve issues with cryogenic operation in time for the JWST launch. The TFI was re-configured to form the basis for the NIRISS instrument that is planned for flight on the space telescope.

Labeled diagrams

File:JWST niriss-layout.jpg|NIRISS

File:JWST FGS opt assembly large.jpg|FGS/NIRISS

File:JWST drawing fgs1.jpg|FGS/NIRISS

Build team

Related institutions and the science team for the instrument includes:

Canada credits work on the FUSE (Far Ultraviolet Spectroscopic Explorer) as helping them prepare for making JWST FGS.

Begoña Vila has been the project's lead systems engineer since 2013.{{Cite news |last=Sacristán |first=Enrique |date=22 August 2016 |title=La NASA premia a una astrofísica gallega por su trabajo en el mayor telescopio espacial |trans-title=NASA Awards a Galician Astrophysicist for Her Work on the Largest Space Telescope |url=https://www.elconfidencial.com/tecnologia/ciencia/2016-08-22/la-nasa-premia-a-una-astrofisica-gallega_1249656/ |url-status=live |archive-url=https://web.archive.org/web/20230419095651/https://www.elconfidencial.com/tecnologia/ciencia/2016-08-22/la-nasa-premia-a-una-astrofisica-gallega_1249656/ |archive-date=19 April 2023 |access-date=31 May 2019 |work=El Confidencial |language=es }}

References

External links

[http://www.stsci.edu/jwst/instruments/niriss/performance-sensitivity NIRISS sensitivity] {{Webarchive|url=https://web.archive.org/web/20161127022114/http://www.stsci.edu/jwst/instruments/niriss/performance-sensitivity |date=2016-11-27 }}
[http://sci.esa.int/jwst/52814-fine-guidance-sensor-part-of-fgsniriss/ ESA – FGS]
[https://jwst-docs.stsci.edu/jwst-near-infrared-imager-and-slitless-spectrograph JWST Near Infrared Imager and Slitless Spectrograph Documentation]

Category:Space program of Canada

Category:James Webb Space Telescope instruments

Category:Spectrographs

Category:Space imagers