NIRSpec

NIRSpec (for Near Infrared Spectrograph) is an instrument on the James Webb Space Telescope (JWST). It has a spectral resolution up to 2700 and a wavelength range of 0.6 to 5.27 μm. It is capable of functioning as a multi-object spectrograph or an integral field spectrograph (i.e., it includes an optional an IFU). The former consists of the ability to configure multiple slits at the focal plane through use of grids of small shutters that can locate several slits within the field of view. The IFU divides a 3"×3" region of the sky into 900 spaxels. For use with neither of these, the spectrograph offers five fixed slits.

NIRSpec offers six gratings and a prism, along with seven filters to impose a wavelength-range. The filters are FX140X, F110W, F070LP, F100LP, F170LP, and F290LP (and a clear filter and a shutter), the number being the wavelength in nanometers, W for wide, X for extremely wide, and LP for long pass, i.e., allows all longer wavelengths. The dispersers are G140M, G235M, G395M, G140H, G235H, G395H, and PRISM, M for medium resolution and H for high resolution (the prism has a much lower resolution). Certain combinations of filter and disperser are designed to capture specific wavelength-ranges. Reported research often quotes the filter/disperser combinations used for of its observations.

The name NIRSPEC is also used for a Keck Observatory instrument.