The Near Infrared Imager and Slitless Spectrograph for the James Webb Space Telescope -- II. Wide Field Slitless Spectroscopy

Understand

We present the wide field slitless spectroscopy mode of the NIRISS instrument on the James Webb Space Telescope.

• This mode employs two orthogonal low-resolution (resolving power $\approx 150$) grisms in combination with a set of six blocking filters in the wavelength range 0.8 to $2.3\,\mu$m to provide a spectrum of almost every source across the field-of-view.
• When combined with the low background, high sensitivity and high spatial resolution afforded by the telescope, this mode will enable unprecedented studies of the structure and evolution of distant galaxies.
• We describe the performance of the as-built hardware relevant to this mode and expected imaging and spectroscopic sensitivity.