F444W F300M F277W F356W F480M F335M F360M F460M F410M F430M LWF1 LWF2 LWF3 LWF4 LWF5 LWF6 LWF7 LWF8 LWF9 LWF10 LWF11 LWF12 F322W2 LWF F250M Imaging pupil F418N Flat field pinholes F323N F466N Corona- graph pupil Corona-graph pupil F470N Outward pinholes LWP1 LWP2 LWP3 LWP4 LWP5 LWP6 LWP7 LWP8 LWP9 LWP10 LWP11 LWP12 Grism 1 Grism 2 F405N LWP SWP F164N Imaging pupil Flat field pinholes DHS 2 Weak lens 2 Corona-graph pupil 1 with wedge Corona-graph pupil 2 with wedge DHS 1 SWP1 SWP2 SWP3 SWP4 SWP5 SWP6 SWP7 SWP9 SWP10 SWP11 SWP12 F140M Weak lens 1 F162M SWP8 Outward pinholes F070W F200W F090W F150W F115W F210M F212N WFS Filter F150W2 F187N SWF1 SWF2 SWF3 SWF4 SWF5 SWF6 SWF7 SWF8 SWF9 SWF10 SWF11 SWF12 Weak lens 3 F182M SWF F225N The background for this poster shows a life size drawing of one NIRCam module. The other side is a mirror image. The two modules are mounted back-to-back with their FOVs adjacent on the sky. Near Infrared Camera (NIRCam) for JWST Michael Meyer, John Stansberry, Erick Young and the NIRCam Team Steward Observatory, University of Arizona Prototype lens mount. Pupil Wheel Collimator Optics Camera Optics NIRCam Pickoff Mirror Telescope Focal Surface Coronagraph Image Masks Coronagraph Wedge JWST Telescope Not to scale NIRCam Optics Field-of-View FPA Coronagraph Image Masks Without Coronagraph WedgeWith Coronagraph Wedge Not to scale Filter Wheel Calibration Source Temperatures of Planets and Brown Dwarfs Survey filters can measure temperatures with an accuracy of 20K For cold objects which may only be detected in the longest wavelength survey filter, temperatures using two medium filters can be measured to 10K. Should be good for coronagraphy of planets! Log g can be estimated from F466N – F470N with limited accuracy – spectra better! Caveat is that this analysis used models (Burrows et al. 2003) – real objects may be less well behaved NIRCam Filters NIRCam’s filter set supports extragalactic surveys, characterization of extra-solar planets, and studies of star formation regions. The filter set covers the entire  m range and will enable a broad variety of projects. Other components in the filter and pupil wheels aid calibration and wavefront sensing. Overview : Overview : NIRCam provides diffraction-limited imaging over the 0.6 to 5  m range. Two science examples are shown below. It uses HgCdTe arrays with a total of 40Mpixels to cover 2.2’x4.4’ arc minutes in two wavelengths simultaneously for efficient surveying. These arrays have excellent performance at the projected ~37K operating temperatures expected on JWST. In 10,000 seconds, NIRCam should detect at 10-  a 10 nJy source at 2  m and a 14 nJy source at 3.6  m. A beamsplitter divides the input light at 2.4  m enabling the observation of two wavelengths at once. In addition to its role as a science instrument, NIRCam is also the facility wavefront sensor. The same arrays used for science imaging will take images using weak lenses in the NIRCam pupil wheel to enable focus diverse wavefront sensing. NIRCam’s optics need to be exquisite to avoid imprinting any NIRCam aberrations on the telescope and hence other JWST instruments. The University of Arizona is leading the NIRCam development effort, Lockheed Martin Advanced Technology Center is responsible for building NIRCam, and Rockwell Scientific Company is providing the detector arrays. Status: Status: NIRCam has already passed its critical design review, and is beginning its construction phase. Two versions of NIRCam will be built: an engineering test unit which will be used in verifying performance of the telescope and associated wavefront sensing and control procedures, and the flight model. Many of the parts for the engineering test unit such as the Be bench, lenses, and detectors are already in production. Prototypes of the cryogenic mechanisms such as the filter wheels and focus adjust mechanism have been built and tested. Several problems that have cropped up have been solved: 1) Detector arrays delaminated from their molybdenum mounts, and 2) cracks developed at two sites on the Be bench as a result of tapping holes. The detector problem was solved by using a stronger epoxy and improved cleaning procedures. The Be bench problem was solved by switching to carbide taps which stay sharp longer and produce cleaner threads. Development of NIRCam is supported by NASA contract NAS NIRCam EPO The NIRCam Team is using facilities on Mt. Lemmon, near Tucson, to run Astronomy Camps for Girl Scout leaders. Other activities include “Ask an Astronomer” days (colorful white board shown from one of these!). NIRCam Coronagraphy NIRCam implements a simple coronagraph that requires no extra moving parts by using a wedge in the pupil wheel to deflect the beam to masks located at the telescope focus. NIRCam will be very effective in studying planets and brown dwarfs in the 4-5  m region as shown below. This plot gives the background as function of distance from a star in a coronagraphic observation and shows that at 4.8  m, groundbased telescopes are always limited by thermal background. Coronagraph occulting masks are just above the pickoff mirror. Plot courtesy of C. Beichman and J. Green. Optical Bench NIRCam’s optics need a rigid base if they are to achieve the required level of performance. The competing need to minimize mass dictated the choice of Be as the bench material. The top two pictures show a plastic bench being used in a practice run of bonding the two halves of a module bench together. The third picture shows part of the Be engineering test unit bench at AXSYS. Aluminum prototype Focal Plane Assembly for holding four 2Kx2K arrays (one shown in the background). CO ice H2O ice CO2 ice N2 ice CH4 ice NH3 ice Pholus WR106 PAH EI 18 L-dwarf T-dwarf W33A Detection of Brown Dwarfs The plot below shows model two brown dwarf spectra from Burrows et al These spectra are for an age of 1 Gyr and a distance of 10 pc. NIRCam easily detects such objects in broadband filters in 10,000 secs which will enable surveys for low mass objects Signal (linear units) Wavelength (µm)