The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 µm. Two nearly adjacent 5.2×5.2 arcmin fields of view in the focal plane are viewed by the four channels in pairs (3.6 and 5.8 µm; 4.5 and 8 µm). All four detector arrays in the camera are 256×256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. IRAC is a powerful survey instrument because of its high sensitivity, large field of view, and four-color imaging. This paper summarizes the in-flight scientific, technical, and operational performance of IRAC.

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The Thermal Infrared Sensor (TIRS) on Landsat 8 is the latest thermal sensor in that series of missions. Unlike the previous single-channel sensors, TIRS uses two channels to cover the 10–12.5 micron band. It is also a pushbroom imager; a departure from the previous whiskbroom approach. Nevertheless, the instrument requirements are defined such that data continuity is maintained. This paper describes the design of the TIRS instrument, the results of pre-launch calibration measurements and shows an example of initial on-orbit science performance compared to Landsat 7.

We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17T17:50 (C7.0), using Quantum Well Infrared Photodetector (QWIP) cameras at an auxiliary of the McMath-Pierce telescope. The flare emissions, the first simultaneous observations in two mid-infrared bands at 5 µm and 8 µm with white-light and hard X-ray coverage, revealed impulsive time variability with increases on time scales of ∼ 4 s followed by exponential decay at ∼10 s in two bright regions separated by about 13 ′′ . The brightest source is compact, unresolved spatially at the diffraction limit (1.3 ′′ at 5 µm). We identify the IR sources as flare ribbons also seen in white-light emission at 6173Å observed by SDO/HMI, with twin hard X-ray sources observed by RHESSI, and with EUV sources (e.g., 94Å) observed by SDO/AIA. The two infrared points have closely the same flux density (f ν , W/m 2 Hz) and extrapolate to a level about an order of magnitude below that observed in the visible band by HMI, but with a flux more than two orders of magnitude above the free-free continuum from the hot (∼15 MK) coronal flare loop observed in the X-ray range. The observations suggest that the IR emission is optically thin; this constraint and others suggest major contributions from a density less than about 3 × 10 13 cm −3 . We tentatively interpret this emission mechanism as predominantly free-free emission in a highly ionized but cool and rather dense chromospheric region.

SHARC II is a background-limited 350 µm and 450 µm facility camera for the Caltech Submillimeter Observatory undergoing commissioning in 2002. The key component of SHARC II is a 12×32 array of doped silicon 'pop-up' bolometers developed at NASA/Goddard. Each 1 mm × 1 mm pixel is coated with a 400 Ω/square bismuth film and located λ/4 above a reflective backshort to achieve >75% absorption efficiency. The pixels cover the focal plane with >90% filling factor. At 350 µm, the SHARC II pixels are separated by 0.65 λ/D. In contrast to the silicon bolometers in the predecessor of SHARC II, each doped thermistor occupies nearly the full area of the pixel, which lowers the 1/f knee of the detector noise to <0.03 Hz, under load, at the bath temperature of 0.36 K. The bolometers are AC-biased and read in 'total power' mode to take advantage of the improved stability. Each bolometer is biased through a custom ∼130 MΩ CrSi load resistor at 7 K and read with a commercial JFET at 120 K. The JFETs and load resistors are integrated with the detectors into a single assembly to minimize microphonic noise. Electrical connection across the 0.36 K to 4 K and 4 K to 120 K temperature interfaces is accomplished with lithographed metal wires on dielectric substrates. In the best 25% of winter nights on Mauna Kea, SHARC II is expected to have an NEFD at 350 µm of 1 Jy Hz −1/2 or better. The new camera should be at least 4 times faster at detecting known point sources and 30 times faster at mapping large areas compared to the prior instrument.