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MIRAC is a Mid-InfraRed Array Camera built for ground-based astronomy by Steward Observatory at the University of Arizona, Harvard Smithsonian Center for Astrophysics, and the Center for Advanced Space Sensing at the Naval Research Laboratory. It utilizes a Hughes Aircraft Co. 20 × 64 pixel arsenic-doped silicon impurity-band-conduction hybrid array with a capacitance-transimpedance-amplifierreadout (CRC 444A). The detector has an operating wavelength range of 2–26 μm . The camera has been operated on the Steward Observatory 1.5- and 2.3-m and the NASA 3-m IRTF telescopes to observe a variety of sources including solar system objects, young stellar objects, planetary nebulae, infrared-luminous galaxies, star forming regions, and brown dwarfs.

We present results using near-infrared (NIR) cameras to study emission. characteristics of common defect classes for integrated circuits (ICs). The cameras are based on a liquid nitrogen cooled HgCdTe imaging array with high quantum efficiency and very low read noise. The array was developed for infrared astronomy and has high quantum efficiency in the wavelength range from 0.8 to 2.5 µm. For comparison, the same set of samples used to characterize the performance of the NIR camera were studied using a non-intensified, liquidnitrogen- cooled, slow scan CCD camera (with a spectral range from 400-1100 nm). Our results show that the NIR camera images all of the defect classes studied here with much shorter integration times than the cooled CCD, suggesting that photon emission beyond 1 µm is significantly stronger than at shorter wavelengths.

Results from MIRAC (Mid-InfraRed Array Camera) observations of the planets Mercury and Jupiter and Comet Swift-Tuttle are presented. A complete description of MIRAC can be found in Hora (1991) and Hoffmann et al. (1993).

We present the main characteristics of a new mid-IR camera, TIRCAM, operating at the 1.5 m Italian Infrared Telescope.

The carbon-rich PPN M 2–9 and IRAS 21282+5050 are known to exhibit UIR feature emission at 7.7, 8.6, and 11.22 µm. The two nebulae have been imaged in the mid-IR with the UA/SAO/NRL Mid-Infrared Array Camera (MIRAC) in bandpasses which include UIR feature emission (8.8 and 11.22 µm). Near-infrared images of the nebulae have also been taken with the NICMOS 3 Hg:Cd:Te array camera at J, H, and K for M 2–9 and at K for IRAS 21282+5050.

We present high-resolution near- and mid-infrared images of the planetary nebula IC 418 at 1.2 (J), 1.6 (H), 2.2 (K), 9.8, and 11.7 µm. The near-IR images were obtained with a 64×64 pixel Hg:Cd:Te array camera, and the mid-IR images were obtained using the new 20×64 pixel Mid-Infrared Array Camera (MIRAC). The size of IC 418 in the near-IR is seen to vary with wavelength, being largest at K and smallest at J. Differences in the morphology of the nebula are seen between the J and K images. There is excess near-IR emission in the center of the nebula, after subtracting out the emission from the central star. Faint halo emission is detected at H and K, extending to a total diameter of approximately 40”. The 9.8 µm emission is distributed nonsyrmnetrically, with the peak in the NE lobe.

Hybrid focal plane arrays using PV HgCdTe have been developed in 128×128 and 256×256 formats mated through indium interconnects to Si CMOS readouts. The band of response for these arrays range from 0.8 – 2.5 microns with pixel sizes of 40microns × 40 microns for the 256×256 and 60×60 for the 128×128 arrays. Mean dark currents lower than 5e- /s at 77K and 0.2- /s at 60K have been measured. Detector noise is typically of the order of 2 E -16 A/Hz at 1Hz under bias of -500V. The arrays exhibit quantum efficiencies of 50%.

A mid-infrared (8–22 μm) camera, equipped with a Hughes hybrid bulk Si:As array detector of 10×64 pixels was developed for the 1.5 m Italian Infrared Telescope (TIRGO). The instrument was used for narrow- band 8–14 μm high-background astronomical observations. Here we present a short description of the camera, including its fast readout electronics and its optical design. When used at TIRGO, the camera has a pixel scale of 1.23 arcsec/pix. From the observations of infrared standard stars we derived a noise equivalent flux density (NEFD) that, for all the filters, is in the range 0.5–0.7 Jy×arcsec-2×min-1/2 and a point spread function (PSF) of the order of 3 arcsec(FWHM). Mosaics of the extended sources Mars at 8.8, 9.8, and 12.5 μm, and of the star forming region Orion BN-KL Nebula at 12.5 μm, are shown. The camera performances are also illustrated on the basis of the image of the post-AGB source CRL618.

We present near- and mid-IR images of the planetary nebulae BD +30 deg 3639 and IC 418, with a unique combination of high spatial and spectral resolution. The mid-IR images were obtained with MIRAC, a new IR array camera. For BD +30 deg 3639, the mid-IR images at 10.0, 11.2, 12.4, 12.8, and 13.2 microns have allowed us to separate the various spectral emission components such as the broad UIR features, the 12.8-micron forbidden Ne II emission feature, and continuum emission, to determine the distribution of these components in the nebula. For IC 418, we have obtained high-resolution images in both the near- and mid-IR. The images in the near-IR at J, H, and K are important for determining the source of the IR excess; one component of the excess is located near the central star. We have also imaged the halo emission at H and K, which has been detected in earlier studies, and have determined its spatial extent. The mid-IR images at 9.8 and 11.7 microns show continuum emission coincident with the ionized zone and suggest that SiC emission originates from the region near the central star.

The carbon-rich PPN M 2–9 and IRAS 21282+5050 are known to exhibit UIR feature emission at 7.7, 8.6, and 11.22 μm. The two nebulae have been imaged in the mid-IR with the UA/SAO/NRL Mid-Infrared Array Camera (MIRAC) in bandpasses which include UIR feature emission (8.8 and 11.22 μm). Near-infrared images of the nebulae have also been taken with the NICMOS 3 Hg:Cd:Te array camera at J, H, and K for M 2–9 and at K for IRAS 21282+5050.

An infrared camera for astronomical research has been developed at the Naval Research Laboratory, Center for Advanced Space Sensing. A series of observations in December 1990 at the 2.3-meter Wyoming Infrared Observatory (WIRO) yielded new astronomical images of the star forming regions M42/IRc 1, NGC 2264/IRS1 and NGC 7538/IRS1 at 12 and 20 microns, in addition to images of a variety of stellar calibrators. Based on a 10x50 element, Si:As BIBIB/SWIFET hybrid array fabricated at Rockwell International, this camera system (IRCAM) achieves its peak sensitivity between 18-22 microns, making it well matched for observing in the 20 micron atmospheric window. Substantial sensitivity is also available at 10 microns so that near simultaneous observations are feasible through both windows. IRCAM employs four, (Delta lambda -> 1.0 microns) filters at 8, 10, 12 and 12.4 microns; a broad band filter: 18-24 microns, as well as standard K, L, and M filters. The array field of view is 20" x 100" with 1.6" pixels surrounded by 0.4" dead space, allowing diffraction limited observing at 20 microns with a 2.3-meter telescope. In this paper, we describe the camera system, and present the results of the astronomical observations conducted at the Wyoming Infrared Observatory.

New observations of DR 15 and 20 are reported as part of a study of compact H II regions in the Cyg X region. The radio and FIR data for these objects, when combined with (C-12)O maps, IRAS imagery, and optical photographs, provide new insights into the structure of this complex region and the nature of the star-formation process there. The observations show that DR 15 may consist of one or two B0 ZAMS stars whose H I regions have formed a low-density cavity within a molecular cloud. DR 20 appears to be a young OB cluster. The cluster is dominated by an O5.5 ZAMS star and also contains an approximately 3500-yr-old B0 star appearing as a compact H II region, along with weak FIR sources that may be B0-star candidates.

Maps are presented with 12-arcmin resolution of the Galactic Center and adjacent galactic plane, from l(Pc) = 359 deg to l(Pc) = 5 deg. The data were obtained with the Steward Observatory's cryogenically-cooled, balloon-borne telescope. The data are from channels filtered for a bandpass of 70 to 110 microns and for a longpass of wavelength greater than 80 microns. For the typical effective temperature of 25 K of a galactic H II region at this spatial resolution, the effective wavelengths of the channels are 93 microns and 145 microns. Continuous emission is mapped along the galactic plane in both wavelengths. There are two contrasts between the immediate vicinity of SgrA l(Pc) smaller than 1 deg, and the galactic plane in general. Firstly, for l(Pi) greater than 1 deg the galactic plane narrows dramatically at 93 microns, while retaining its width at 145 microns. Secondly, the individual sources at l(Pc) (which are associated with H II regions) have greater peak brightness in the 145-micron channel than the 93-micron channel, while SgrA has approximately equal peak brightness in each. The maps demonstrate the importance of submillimeter wavelengths to galactic surveys.

The spectral response of an n-type InSb bolometer and a Golay detector were compared between about 10 and 100 cm−1. The optical systems were held nearly constant and major wave number dependent deviations were removed from the data. The relative responsivities are given with the detector, cathode followers, and preamplifiers treated as a single component with the detector.

We measured the anisotropy of the cosmic background radiation at the angular scale of 2/sup 0/ in the millimetric wavelength region, in the course of the NASA-ESA ASSESS II Mission. We set upper limits on the anisotropy in several sky regions, the most stringent one being ..delta..T/T

Two types of superconducting electromagnetic actuators-linear and angular-for precise control of Fabry-Perot spectrometer etalons at liquid helium temperature were manufactured and tested successfully. The linear displacement unit (45 Newtons/Amp) has maximum travel of ±44 um with off-axis deviation of less than 1.5 arcseconds for 15 um path. The angular unit has maximum tilt of ± 8 arcminutes and can maintain parallelism of Two etalons to better than 0.3 arcsecond of angle by compensating the differential contraction upon coaling and off-axis deviation of the linear displacement unit. These actuators are proving especially useful in low temperature infrared instrumentation where other choices, such as piezoelectric crystals, fail and where essentially zero power dissipation permits low infrared backgrounds to be maintained along with long cryogenic lifetimes.

Results are reported for measurements of IRC + 10216 at 100 microns made with the 91-cm telescope of NASA's Kuiper Airborne Infrared Observatory. The IR photometer employed consisted of a gallium-doped germanium photoconductive detector with a MOSFET preamplifier and load resistor. Signals obtained from the source at modulation frequencies of 30 and 100 Hz are plotted, and the 100-micron flux measurements are shown to be in agreement with previous bolometric measurements. It is noted that the sensitivity of the photoconductive detection system is comparable to that of the conventional bolometers that have been used in airborne IR observations.

Limb darkening on earth night side observed by Aerobee rocket, with explanation based on atmospheric opacity in water vapor and carbon dioxide bands

AFGL will begin a series of rocket borne experiments in the summer of 1981 to survey the sky in the infrared. Two cryogenically cooled telescopes systems will be used, each with a 36 cm diameter primary aperture. One system is cooled with super-critical helium and surveys in three broad spectral bands centered at 11, 20.5 and 27 um. The other telescope system has a super-fluid helium reservoir and incorporates long wavelength arrays centered at 40 and 95 pm in addition to the three shorter wavelength arrays. These experiments will be flown on ARIES sounding rockets to an altitude of 380 km. Each experiment will cover 22 to 35 percent of the sky to a noise equivalent flux density (NEFD) of 1 to 3 x 10-17wcm-2 in each of the spectral bands. This is a factor of about 20 improvement over the previous instruments we used for the 11 and 20 pm observations. The survey instrumentation is described in this report as well as how the experiment will be conducted.

The increasing interest in the application of bolometers and photoconductors in infrared astronomy has stimulated considerable research effort during the past few years in improving the sensitivities of these detectors under low and high background conditions. A review of these detectors will be given and their applications in photometry and spectroscopy with ground based and airborne infrared astronomical systems will be discussed.

Results concerning zodiacal dust emission are reported from an IR sky survey experiment performed during a balloon flight on July 30, 1984 which explored five wavelength bands centered at 11, 19, 50, 108, and 225 microns. The dust density n decreases at a rate slower than r exp -1.3 with increasing heliocentric distance. The trend of n depends critically on the radial variation of the temperature which, in turn, depends on the chemical composition of the grains. The spatial distribution of the dust is in good agreement with that previously inferred from IR measurements. A comparison between IR and optical observations points out the uncertainties affecting the estimates of the dust density obtained with both methods. The emission spectrum of the dust is used to discriminate among the different species of grains, showing that the observations can be accounted for by an appropriate mixture of graphite and silicates. 18 references.

We have developed a large beam, five-band IR differential photometer, covering the range from 10 to $ 200 μm, devoted to the study of diffuse emission of galactic and extragalactic origins. Here we describe in detail the main features of the experimental apparatus and its calibration. The experiment was flown on a stratospheric balloon on 30 July 1984, collecting data for about 15 hours.

The objective of the Far Infrared Sky Survey Experiment (FIRSSE) is to measure the spatial and brightness distribution of the celestial background and astronomical sources in the wavelength region between 8 µm and 120 µm. A superfluid helium (2.2K) cooled sensor with background photon noise limited detector arrays will be flown on an Aries sounding rocket. This paper outlines the current design concept of the sensor and focal plane array layout of the experiment.

Photoconductive detectors in the 10-1000μm range have been developed and flown in rocket borne liquid helium cooled telescopes for sky survey and auroral emission studies. Measurements under background limited conditions have been made in the spectral range of 60-300μm using the 30cm telescope aboard the NASA Lear Jet. We present the results of the detector sensitivities used under these two environments.© (1975) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Near infrared detector technology in the 10-30 μm band have been developed for use in liquid helium cooled telescopes both for celestial background measurements and for target identifications. Focal plane arrays using multidetector elements with charge coupled devices are being developed for infrared imagery. Research and development technology are now in progress for long wavelength (30 μm - 125 μm) detectors to be used in cryogenically cooled infrared telescopes to be used in satellite infrared experiments.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A Ge:Ga photoconductive detector at l00μm and a GaAs epitaxial photoconductive detector at 285μm has been optimized for sensitivity comparison with a conventional bolometer system of Yerkes Observatory. The response of the photoconductive detectors were studied in the laboratory under two background conditions: baffles and Fabry Optics. A direct comparison of the photoconductive detectors to the bolometer will be made on the 91.5 cm telescope aboard the NASA C-141 Airborne Infrared Observatory.

The objectives of the Far Infrared Sky Survey Experiment (FIRSSE) are to obtain unbiased measurements of the position and radiance of infrared celestial sources in five spectral bands between 8 and 120 µm. The superfluid helium cooled sensor will be flown on an Aries sounding rocket sometime in 1980. The status of the sensor is presented in this paper.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The extension of astronomy in the wavelength region of 1 μ to 1 mm has in the past been limited by lack of detectors of high sensitivity and by the obscuration of the Earth’s atmosphere. Ground-based near infrared astronomy could be carried out within certain partial windows: i.e. from 2.1 μ to 2.4 μ, 3.5 μ to 4.0 μ, 4.6 μ to 4.7 μ, 8–13 μ, and 20–25 μ. The region from 25 μ to 2 mm is completely opaque and measurements have to be carried out from above the atmosphere using aircraft, balloons, or rocket experiments.

DURING the past few years, there have been conflicting measurements of the night sky background in the region around 100 µm. Houck and Harwit1 reported a radiance > 10−9 W cm−2 sr−1 whereas McNutt and Feldman2 did not observe this radiance to a limit of 4 × 10−11 W cm−2 sr−1, both referred to 100 µm. Recent measurements by Pipher et al.3 and Blair4 support the lower limit, but in our most recent experiment we find the high value originally observed by Houck and Harwit. We have also observed a high background signal in a band around 280 µm but not at shorter wavelengths (10 to 30 µm). The two high measurements were made soon after astronomical twilight whereas all of the low results were obtained near local midnight. This suggests that the source of the radiation is local rather than galactic or extra-galactic.

Far-infrared maps are presented for three young H II regions in the Cygnus X region. DR 6 and 7 were mapped in the wavelength band from 40 to 250 microns at 1 arcmin resolution, while DR 22 was mapped in the same band and also at 100-250 microns, providing dust temperature and optical depth information. New VLA maps of these sources are also presented. It is concluded that DR 6 and 7 are powered by clusters of late O or early B type stars, with ages 100,000 yr or less, while DR 22 appears to be produced by a single O6 ZAMS star. Existing (C-12)O maps suggest that the formation of these objects occurred near the edges of molecular clouds.

The W28 supernova remnant molecular cloud complex has been surveyed in the 40-250 micron spectral range with a three-sigma sensitivity of 100-165 Jy per beam. Only two sources have been found. One, located near the center of the SNR, has a luminosity of 54,000 solar luminosities and can be identified with the thermal radio source G6.6-0.1. The energizing source is probably an O-type ZAMS star. The second source, which is near the boundary of the SNR at a sharp gradient of OH absorption, has a luminosity of 6000 solar luminosities and has no radio counterpart. It is best explained as a B1 ZAMS star or a pre-main sequence object presumably formed from the impact of an expanding SNR with a molecular cloud. No far-IR emission is observed at the position of the CO molecular cloud, which seems to have been impacted by the SNR.

A far-IR map with 1 arcmin resolution was obtained of the W51 H II region molecular cloud complex. The 40-120 microns survey was performed to study embedded sources which excite the H II gas. The far-IR emission distribution overlapped radio emissions from the region, implying that the extended dust clouds were heated by the same sources as the H II regions. Four compact sources were characterized and associated with concentrations of luminosities that suggested a scarcity of low-mass stars. The brightest source, labeled W51-I, has a luminosity/mass ratio of 150, high enough to indicate a burst of massive O star formation. No triggering mechanism was identified for the burst of star formation.

A liquid-helium-cooled Ebert-Fastie grating spectrometer for use in a sounding rocket is described. Twelve detectors and associated filters separate the 5-70-microm spectral range into twelve intervals, each of which is scanned as the grating is rotated. The instrument was launched into an aurora from Fort Churchill, Canada, but a cryogenic failure occurred early in the flight, and only a small amount of data was obtained.

A telescope for rocket-borne ir astronomy is described. It consists of a 166-mm cassegrainian telescope cooled to liquid helium temperature and operated with a total radiation chopper. Details of the optical, cryogenic, and electronic designs are given.

We have constructed a liquid nitrogen cooled telescope that was flown in an Aerobee 150 rocket. The telescope allows measurement of absolute ir signal strengths from astronomical objects in the wavelength range out to about 7.5 micro. In contrast to ground-based telescopes, it can observe diffuse as well as discrete astronomical sources.