The Near-Infrared Camera (NIRCam) is one of Webb’s four scientific instruments. NIRCam is Webb’s primary near-infrared imager, providing high-resolution imaging and spectroscopy for a wide variety of investigations. Because NIRCam is the only near-infrared instrument with coronagraphic and time-series imaging capabilities, it is crucial for many exoplanet studies. In addition to imaging and spectroscopy, NIRCam is also part of Webb’s wavefront sensing and control system, which detects and corrects for slight irregularities in the shape of the primary mirror or misalignment between mirror segments, giving the telescope the ability to focus clearly on objects near and far. NIRCam was built by a team at the University of Arizona and Lockheed Martin’s Advanced Technology Center.
NIRCam Components Cameras capture two-dimensional images of regions of space. Spectrographs spread light out into a spectrum so that the brightness of each individual wavelength can be measured. Coronagraphs are opaque disks used to block the bright light of stars in order to detect the much fainter light of planets and debris disks orbiting the star.
NIRCam Wavelength Range NIRCam is designed to capture light ranging in wavelength from 0.6 microns (visible red) to 5 microns (mid-infrared).
NIRCam Fields of View An instrument’s field of view is the amount of sky that it can observe at any given point in time. (The actual area that can be observed depends on the distance of the object being observed.) In this graphic, a Hubble Space Telescope image of the Whirlpool Galaxy (M51) is shown for scale. The image covers an area of 9.6 × 6.6 arcminutes. (The full Moon has a diameter of about 31 arcminutes across the sky.) NIRCam has two main fields of view, each of which covers an area of 2.2 × 2.2 arcminutes. Its coronagraphic field of view is smaller.
NIRCam Imaging Modes Standard Imaging is the equivalent to basic digital photography and involves capturing pictures of a wide variety of objects and materials in space that emit or reflect infrared light. Coronagraphic Imaging (sometimes called high-contrast imaging) involves using a coronagraph to block the light of a star in order to reveal the much dimmer light of nearby objects, such as exoplanets and debris disks. Time-Series Imaging involves capturing a series of images at regular intervals in order to measure changes over time. Time-series can be used to track changes in the brightness of a star or can be combined with coronagraphic imaging to track the motion of a planet.
NIRCam Spectroscopy Modes Wide-Field Slitless Spectroscopy involves capturing the overall spectrum of a wide field of view: a field of stars, part of a nearby galaxy, or many galaxies at once. Time-Series Spectroscopy involves capturing the spectrum of an object or region of space at regular intervals in order to observe how the spectrum changes over time. Time-series spectroscopy is used to study planets as they transit their stars.
Credits
Illustration
NASA, ESA, Andi James (STScI)
