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Shocked molecular hydrogen has been observed around the nucleus of the nearby galaxy, NGC 253. This galaxy has a relatively modest luminosity (approx. 3 x 10 to the 10th power solar luminosities) and appears to have no distortions or companions that would indicate a possible interaction. The energy of the galaxy appears to be derived primarily from a starburst. Thus, our observations have caused us to examine the starburst process in some detail to identify how the molecular hydrogen is excited. It is proposed that the molecular hydrogen emission is produced by collisions of dense molecular clouds accelerated by supernovae explosions. Within the nucleus, this process occurs early in the life of the starbust. This suggest a sequence of nuclear starburst development; examples along this sequence from young to old would include NGC 253, M82, NGC 1097, and M31.

The 32 x 32 HgCdTe array manufactured by Rockwell International was proven to be a highly competitive detector type for use at wavelengths shorter than 2.5 microns. The goal of a K=+16 sky survey using this array attached to the Steward Observatory Transit Telescope is clearly within reach. The detector material exhibits high quantum efficiency and low dark currents indicating that its usefulness may extend beyond its use with a CCD readout on groundbased telescopes.

Improved spectrophotometry of Triton at 2.16 microns was obtained with the MMT infrared photometer at a resolution of 1.0 percent. The observations do not reveal an absorption feature due to liquid nitrogen. Three explanations are consistent with this finding: (1) there is liquid nitrogen on the surface but it is not distributed uniformly; (2) the feature varies with time, e.g., it is sometimes obscured by cloud cover; and (3) the feature might be relatively broad.

The solar-analog method is used to determine the absolute calibration of photometry in the J, H, K, L, and M bands to an accuracy of 3 percent, (5 percent at M). This calibration agrees well with the direct calibration obtained by Blackwell et al. (1983); this agreement gives confidence that the calibration is known to an accuracy of 2 percent to 3 percent. The agreement also implies that the behavior of solar type stars is well understood in the infrared and that such stars make reliable standards for calibration of nonstandard photometric bands and for planetary reflectance studies. Both methods indicate that Vega is slightly brighter than indicated by atmospheric models.

Two new direct calibrations at 10 and 20 microns are presented in which terrestrial flux standards are referred to infrared standard stars. These measurements give both good agreement and higher accuracy when compared with previous direct calibrations. As a result, the absolute calibrations at 10 and 20 microns have now been determined with accuracies of 3 and 8 percent, respectively. A variety of absolute calibrations based on extrapolation of stellar spectra from the visible to 10 microns are reviewed. Current atmospheric models of A-type stars underestimate their fluxes by about 10 percent at 10 microns, whereas models of solar-type stars agree well with the direct calibrations. The calibration at 20 microns can probably be determined to about 5 percent by extrapolation from the more accurate result at 10 microns. The photometric system at 10 and 20 microns is updated to reflect the new absolute calibration, to base its zero point directly on the colors of A0 stars, and to improve the accuracy in the comparison of the standard stars.

Five-color (wavelength = 0.36-0.85 microns) and thermal infrared (wavelength = 22.5 microns) photometric observations of the unusual asteroid 2060 Chiron were made. Between 0.36 and 0.85 microns, Chiron's reflectance spectrum is similar to those of C-class asteroids as well as Saturn's satellite Phoebe. However, the thermal IR measurements imply an albedo greater than 0.05 (i.e., a diameter of less than 250 km at the 2-sigma level) that is probably higher than those of C-class asteroids or Phoebe.

In each of the present four simultaneous spectra covering the radio-through-X-ray regimes, the IR-UV synchrotron continuum dominates the total observed power and presumably becomes opague between 10 to the 11th and 10 to the 13th Hz. Nonsimultaneous observations were also conducted, over a longer time period, in order to study long- and short-term variability at X-ray, optical, and radio frequencies. These data indicate that the rapid and dramatic variations evident at IR and optical wavelengths are absent at radio and X-ray frequencies, supporting a view of IR-UV flux emanation from a small region, while the X-rays are produced by the inverse Compton process in the radio-emitting region. Particles, photons and magnetic field may not be far from equipartition in this region. Theoretical suggestions are developed regarding the radial behavior of the electron density and magnetic field.

Linear polarimetry of Ceres at 10 micron is presented. These data represent the first published polarization measurements of an asteroid in the thermal infrared. It is found that Ceres is polarized at the 0.2-0.6 percent level. This data set is compared with theoretical models of the linear polarization of emitted radiation from a spherical plane. These models are used to derive the pole position and thermal inertia of Ceres. Ceres is best fit with a thermal inertia of 0.0010 + or 0.0003 cal (sq cm K) per square root of second and a pole orientation of beta(p) = 36 deg + or - 5 deg + or -5, lambda(p) = 270 deg + or - 3. It is concluded that 10 micron polarimetry is a potentially powerful technique for remotely sensing the pole orientation and thermal inertia of asteroids.

Results of observations of the reflected light in the 1-5 micron region of the spectrum from the Comet Bowell are presented as part of the attempt to directly detect the presence of frozen volatiles in the nucleus of a comet. A deep absorption at 3.25 microns is detected in Comet Bowell which is due to the presence of H2O ice. While other volatile ices have absorption features near 3 microns, it is shown that only H2O ice is a plausible identification at the heliocentric distance of Comet Bowell during the observations (3.4 AU) since only H2O grains are stable enough to have produced the observed absorption. The implications of these findings for models of cometary nuclei are examined.

Infrared observations of Comet Bowell represent the first search for frost signatures in a comet beyond 2 AU from the sun. Broad- and narrowband photometry has been obtained as well as CVF spectrophotometry of this comet and there is no evidence for absorption features in the spectral area between 1.25 and 2.3 microns. Models of the coma have been generated which constrain the volatile content of the grains an; are in agreement with the observed albedo. The darkness of the coma particles at large heliocentric distances indicates a low albedo nucleus as well. Brightness variations during the observing period seem to indicate an active nucleus at 4.5 AU from the sun.

Nearly simultaneous photometry of the reflected and thermal infrared spectra of periodic comets Encke, Chernykh, Kearns-Kwee, Stephan-Oterma, and Tuttle are presented. The 10-micron silicate emission feature has been detected for the first time in periodic comets and was observed in three of these objects. The albedo of the dust particles in the comae of these comets is calculated and compared to that of Comet Kohoutek. The peculiar behavior of the dust in Comet Encke is discussed.

Results are presented from an intensive optical and IR monitoring program of the flux and polarization characteristics of BL Lac. It is found that the polarization variations increase in amplitude with increasing time interval, and that the path traced out by the polarization vector in the Q-U plane is a random walk. In view of earlier measurements of BL Lac, the polarization fluctuations can be represented at low frequencies by the flat power spectrum of white noise, up to a frequency of 0.05 cycles/day. Above this frequency, the spectrum steepens to that of a random walk. A model for BL Lac suggested by the polarimetric noise can be constructed from independent sources of light with randomly oriented, strong polarization. Small random differences in spectral index from source to source could also explain the variable wavelength dependence of polarization.

Photometry at 3.5 microns was taken with the Infrared Telescope Facility of the Multiple Mirror Telescope to obtain an improved IR spectrum of Triton. The observations show features that are not in detailed agreeement with previous identifications of methane or methane frost, although the general spectral behavior leading to such identifications has been confirmed. It is believed that a combination of surface and atmospheric absorptions may resolve some discrepancies; for instance, many hydrated minerals and frosts which are dark between 3.0 and 4.0 microns may combine with a carbon monoxide atmosphere to yield the data in question.

Infrared thermal emission measurements are reported of 1862 Apollo, which is the type example of an earth-crossing asteroid. A geometric albedo of 0.21 plus or minus 0.02 is derived which is within the albedo range of the S class of asteroids. The effective diameter was observed to vary with rotation from 1.2 plus or minus 0.1 to 1.5 plus or minus 0.1 km.

New observations at 1.6-3.45 microns confirm the presence of a dramatic (change in spectral index of approximately 1) break between radio-IR wavelengths and 6,000 A in the spectrum of the M87 jet. These data, in combination with data taken in other spectral regions, show that the individual knots in the M87 jet have nearly the same spectral indices and nearly the same large (change in spectral index of approximately 1) spectral break. This large spectral break and the constancy of spectral properties between the knots pose serious constraints for models of the M87 jet.

Two micron linear polarimetry of the S 106 and NGC 7538 E regions reveal the presence of infrared reflection nebulae, which may confuse the count of luminosity sources in a region of star formation. S 106 and NGC 7538/IRS 9 are considered the only luminosity sources in their respective regions, and the polarization of S 106/Source 3 is probably due to absorption by aligned grains. Moreover, the reflection nebula model for NGC 7538 E is best supported if the polarization of NGC 7538/IRS 9 itself is due to the absorption by aligned grains.

Medium-resolution infrared (1-2.5 microns; Delta-lambda/lambda = 0.05) photometry of Triton, Titania, and Hyperion and medium-resolution (1.5-2.4 microns; Delta-lambda/lambda not greater than 0.01) spectroscopy of Triton are presented. Hyperion and Titania have spectra roughly similar to the laboratory spectrum of water frost, while the spectrum of Triton is inconsistent with the spectra of frosts likely to be major surface constituents.

Techniques are described to allow operation of discrete solid state detectors at 4 K with optimized junction field effect transistor (JFET) amplifiers. Three detector types cover the 0.6-4 micron spectral range with a noise equivalent power (NEP) of approximately 10 to the -16th per sq rt Hz for two of the types and potential improvement to this performance for the third. Lower NEPs can be anticipated at longer IR wavelengths.

Techniques are described to allow operation of discrete, solid state detectors at 4 K with optimized JFET amplifiers. Three detector types cover the 0.6 to 4 mm spectral range with NEP approximately equal to 10 to the 16th power Hz (-1/2) for two of the types and potential improvement to this performance for the third. Lower NEP's are anticipated at longer infrared wavelengths.

Near-infrared plates of a region in Cygnus show an extremely red nebula, about 25 arc seconds in diameter, which is displaced by about 18 arc seconds from UOA 27, an object with infrared and microwave properties similar to those of the Becklin-Neugebauer point source in Orion. This nebula may be reflecting light from the same obscured star which is the energy source for UOA 27, and could therefore provide a unique, though indirect, means of investigating the nature of stars which heat the BN point source and related objects.

Optical and infrared polarimetric and photometric observations of the BL Lacertae object B2 1308+326 during its high-luminosity outburst in the spring of 1978 are reported. The energy distribution, polarization at 0.6 and 2.2 microns, flux and polarization variability and position angle and strength of polarization variations of B2 1308+326, which has a luminosity greater than 10 to the 48th ergs/sec, are observed to be similar to those of BL Lac objects of much lower luminosity, suggesting the same emission process. Models of BL Lac object emission accounting for the high luminosity of B2 1308+326 are examined, and the isotropic synchrotron model is found to be more applicable to the optical and infrared emission of BL Lac objects than a model invoking relativistically enhanced emission.

Broadband (J, H, K and L) and narrowband (1.5- to 3.7-micron) infrared photometry of Pluto has been conducted in order to check previous ambiguous observations of methane frost on the planet's surface. In detail, the match between a laboratory spectrum of methane frost and the observed spectrum of Pluto is not good. Nevertheless, the photometric observations suggest the presence of methane in some form.

Broadband visual and 10.6-micron photometry of 1580 Betulia was obtained during its close approach to earth in May 1976. The photometry was analyzed by using the 'radiometric method' to derive the radius (2.10 + or - 0.40 km) and albedo (0.108 + or - 0.012) of Betulia. Radar and polarimetric results indicate a radius greater than 3.0 km and a geometric albedo of about 0.05. To be compatible with these results, Betulia was also modeled as having a surface with the thermal characteristics of bare rock rather than those of the 'lunar' regolith model used for previous analysis of radiometry of other asteroids. A 3.7-km radius and a geometric albedo of about 0.04 are compatible with all available observations. Betulia is the first Mars-crossing asteroid found to have such a low albedo, which may be indicative of carbonaceous surface material.

The paper presents results of a search for optical counterparts of confirmed AFCRL infrared sources using the Palomar Sky Survey and direct photography with the Carnegie image tube camera. Positions and identification charts for possible counterparts to 26 AFCRL sources are presented. A list of AFCRL sources for which no optical counterparts were found is given, and some arguments to explain why the results of this search were negative are presented.