The Multiband Imaging Photometer for Spitzer (MIPS) provides long-wavelength capability for the mission in imaging bands at 24, 70, and 160 m and measurements of spectral energy distributions between 52 and 100 m at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point-spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The 24 m array has excellent photometric properties, and measurements with rms relative errors of about 1% can be obtained. The two longer-wavelength arrays use detectors with poor photometric stability, but a system of onboard stimulators used for relative calibration, combined with a unique data pipeline, produce good photometry with rms relative errors of less than 10%.

ABSTRACT. We describe the data reduction algorithms for the Multiband Imaging Photometer for Spitzer (MIPS). These algorithms were based on extensive preflight testing and modeling of the Si:As (24 mm) and Ge:Ga (70 and 160 mm) arrays in MIPS and have been refined based on initial flight data. The behaviors we describe are typical of state-of-the-art infrared focal planes operated in the low backgrounds of space. The Ge arrays are bulk photoconductors and therefore show a variety of artifacts that must be removed to calibrate the data. The Si array, while better behaved than the Ge arrays, does show a handful of artifacts that must also be removed to calibrate the data. The data reduction to remove these effects is divided into three parts. The first part converts the nondestructively read data ramps into slopes while removing artifacts with time constants of the order of the exposure time. The second part calibrates the slope measurements while removing artifacts with time constants longer than the exposure time. The third part uses the redundancy inherent in the MIPS observing modes to improve the artifact removal iteratively. For each of these steps, we illustrate the relevant laboratory experiments or theoretical arguments, along with the mathematical approaches taken to calibrate the data. Finally, we describe how these preflight algorithms have performed on actual flight data.

Analysis of dentitions belonging to 324 prehistoric and protohistoric Aleuts, Eskimos and northern Indians, all of whom were regularly meat-eaters, reveals a significant difference between Eskimos and Aleut-Indians for a little known type of tooth wear. This wear is characterized by severe crushing and/or flaking of the crown surface of one or more teeth (termed "pressure-chipping"). It occurs chiefly i n dentitions of high arctic Eskimos of Alaska, Canada, and Greenland, and significantly less often in the teeth of Kodiak Island Eskimos, Aleuts and northern Indians. Sex differences do not exist but pressure-chipping occurs significantly more often in adult (21-x years) than in non-adult (0-20 years) Eskimos. The exact mechanism(s) responsible for pressure-chipping is unknown, although ethnographic accounts of Eskimo eating habits suggest that crushing of hard substances such as bone was involved. The severity of this wear could have contributed to the selection for, or preservation of, large and complex crowns in high arctic Eskimos. Pressure-chipping is offered as evidence favoring the view that tooth size (longevity) may have had in the past some adaptive value.

We present Spitzer Space Telescope early release observations of Fomalhaut, a nearby A-type star with dusty circumstellar debris. The disk is spatially resolved at 24, 70, and 160 m using the Multiband Imaging Photometer for Spitzer (MIPS). While the disk orientation and outer radius are comparable to values measured in the submillimeter, the disk inner radius cannot be precisely defined: the central hole in the submillimeter ring is at least partially filled with emission from warm dust, seen in Spitzer Infrared Spectrograph (IRS) 17.5-34 m spectra and MIPS 24 m images. The disk surface brightness becomes increasingly asymmetric toward shorter wavelengths, with the south-southeast ansa always brighter than the north-northwest one. This asymmetry may reflect perturbations on the disk by an unseen interior planet.