This letter presents the first results of the mid-infrared spectrum (4.5–11.7 μ m) of the diffuse emission near to the galactic plane (l ∼ 50°; |b| ≤ 5° obtained by the mid-infrared spectrometer on board the Infrared Telescope in Space mission. The results clearly demonstrate the presence of unidentified infrared emission (UIR) bands at 6.2, 7.7, 8.6, and 11.3 μm in the diffuse galactic emission. The distribution of the UIR bands correlates well with the IRAS 100 μm map, suggesting that the UIR-band emitting material is well mixed with the classical dust grains in general interstellar space. The present results indicate that more than 70% of the IRAS 12 μm flux diffuse emission is emitted in the spectral range 8–11.7 μm, and that most of the 12 μm excess comes from the features associated with the UIR bands.

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We present 3.6, 4.5, 5.8, 8.0, 24, and 70 m images of the Crab Nebula obtained with the Spitzer Space Telescope IRAC and MIPS cameras, low-and high-resolution Spitzer IRS spectra of selected positions within the nebula, and a near-infrared ground-based image made in the light of [Fe ii] 1.644 m. The 8.0 m image, made with a bandpass that includes [Ar ii] 7.0 m, resembles the general morphology of visible H and near-IR [Fe ii] line emission, while the 3.6 and 4.5 m images are dominated by continuum synchrotron emission. The 24 and 70 m images show enhanced emission that may be due to line emission or the presence of a small amount of warm dust in the nebula on the order of less than 1% of a solar mass. The ratio of the 3.6 and 4.5 m images reveals a spatial variation in the synchrotron power-law index ranging from approximately 0.3 to 0.8 across the nebula. Combining this information with optical and X-ray synchrotron images, we derive a broadband spectrum that reflects the superposition of the flatter spectrum of the jet and torus with the steeper spectrum of the diffuse nebula. We also see suggestions of the expected pileup of relativistic electrons just before the exponential cutoff in the X-ray. The pulsar, and the associated equatorial toroid and polar jet structures seen in Chandra and Hubble Space Telescope images (Hester et al. 2002), can be identified in all of the IRAC images. We present the IR photometry of the pulsar. The forbidden lines identified in the high-resolution IR spectra are all double due to Doppler shifts from the front and back of the expanding nebula and give an expansion velocity of %1264 km s À1 .

The Japanese satellite-borne infrared telescope, the Infrared Telescope in Space (IRTS), has completed a successful survey of a portion of the infrared sky. The IRTS consists of a 15 cm telescope cooled with superfluid liquid helium, and is installed on board the Space Flyer Unit (SFU) spacecraft. The SFU was launched on 1995 March 18 UT. The sky survey by the IRTS started on March 29 UT, and was completed on April 25 UT after exhausting its liquid helium. The cryogenic system operated as designed, and maintained the telescope and the focal-plane instruments at a stable temperature of 1.9 K for 38 days. The four focal-plane instruments, which together covered almost the entire infrared wavelength range, observed a sky area of about 2700 deg2 and returned a wealth of new data on a variety of objects, including the zodiacal light, interstellar gas and dust, near-infrared cosmic background light and point sources.

We describe the design of Bolocarn, a bolometric camera for millimeter-wave observations at the Caltech Submillimeter Observatory. Bolocam will have 144 diffraction-limited detectors operating at 300 mK, an 8 arcrninute field of view, and a sky noise limited NEFD of 35 mJy Hz per pixel at A = 1.4 mm. Observations will be possible at one of A = 1.1, 1.4, or 2.1 mm per observing run. The detector array consists of sensitive NTD Ge thermistors bonded to silicon nitride micromesh absorbers patterned on a single wafer of silicon. This is a new technology in millimeter-wave detector array construction. To increase detector packing density, the feed horns will be spaced by 1.26fA (at A = 1.4 mm), rather than the conventional 2fA. DC stable read out electronics will enable on-the-fly mapping and drift scanning. We will use Bolocam to map Galactic dust emission, to search for protogalaxies, and to observe the Sunyaev-Zel'dovich effect toward galaxy clusters.