Fine_Guidance_Sensor_and_Near_Infrared_Imager_and_Slitless_Spectrograph
Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph
Canadian aligner and spectrometer on JWST
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.[1] The FGS/NIRISS was designed by the Canadian Space Agency (CSA) and built by Honeywell[2] 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).[1] FGS-NIRISS observes light from the wavelengths of 0.8 to 5.0 microns.[1] The instrument has four different observing modes.[3]
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.[3][4] The spectroscopic mode is capable of doing exoplanet spectroscopy.[5] 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.[6] The field of view is 2.2' × 2.2' which gives a plate scale of about 0.065 arcsec/pixel.[6]
The FGS will help the telescope aim and stay pointed at whatever it is commanded to look at.[7] 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.[8]
NIRISS is designed for performing:[9][10]
- 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.[9]
The Engineering Test Unit of the FGS was delivered to NASA in 2010.[11] The flight units were planned to be delivered later after the ETU, which enabled testing with other JWST hardware.[11] The flight units of FGS/NIRISS were delivered to NASA in August 2012.[12]
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