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Gum Nebula size, density and electron temperature data from RAE-1 and OGO-5 satellites and ground based telescopes observations, correlating with Vela X supernova outburst
Results of observations of the spectral reflectance properties (0.3 to 1.1 micron) of a number of lunar mare, upland, and bright crater areas with the use of ground-based telescopes. These new data are discussed in view of earlier studies in an attempt to provide a basis for more detailed interpretation. The spectral reflectivity curves (0.3 to 1.1 micron) for all lunar areas studied consist of a positive sloping continuum with a superimposed symmetric absorption band centered at 0.95 micron. Upland, mare, and bright crater materials can be identified by their spectral curves. The curves for upland and mare regions show a range of shapes from fresh, bright craters to progressively darker background material that correlates with the apparent age of the surface features. The observed upland material has uniform spectral properties, but the mare material shows some variety, probably due to Ti(3+) dispersed in lunar-soil glass. Copernicus and Aristarchus appear to have exposed upland material from beneath the mare but Kepler has not. This observation suggests that the mare is no deeper than about 15 km in the Copernicus area and about 6 km deep in the Aristarchus area, but in the Kepler area the mare must be at least about 5 km deep.
The research to develop a spectrometer to be used with a ground based telescope is described. Two liquid helium cooled infrared spectrometers were designed and built. The first, has a Cassegrain optical system and a variable focal length between 51.4 cm and 92.6 cm. It is capable of a resolution of 500. The second, has a focal length of 19.1 cm and has a resolution of 100. Both spectrometers have been operated at 10-30 microns. Sample spectra are included.
Large and small scale albedo markings obtained from Mariner 9 photographs and ground based telescope observations are shown on quadrangle charts with a scale of 1:5,000,000. Mercator and stereographic projections at the same scale are presented of the various regions of Mars along with explanatory information about their preparation. Changes in the albedo for the Solis Lacus area were observed and are compared with previous data for the same region. Large scale relief maps covering up to 1.7 million sq miles of the Martian surface are included.
The infrared spectral range extends approximately from 1 micron to 1000 microns. Observations in infrared astronomy are made with the aid of ground-based telescopes and telescopes flown in aircraft, balloons, or rockets. Advantages and drawbacks of infrared studies conducted by different approaches are discussed. Infrared astronomers are looking forward to observations made from orbiting spacecraft. Present plans call for placing a large telescope aboard the Space Shuttle Orbiter for short missions lasting from seven days to three weeks several times a year. However, the occurrence of a pollution of the spacecraft environment by dust particles and gases coming from the spacecraft might present a problem for the observations. Possible approaches for solving this problem are discussed.
Ground based telescopic observations of Titan and outer planet atmospheres are evaluated for their abundances and an effort is made to deduce the various hydrogen-to-carbon ratios. Jupiter and Saturn atmospheres seem to have roughly solar abundances as far as hydrogen and methane are concerned; for Uranus, Titan and Neptune these ratios are way down.
The production of simple and rugged photon-counting detector arrays has been made possible by recent improvements in the performance of the microchannel array plate (MCP) and by the parallel development of compatible electronic readout systems. The construction of proximity-focused MCP arrays of novel design in which photometric information from (n x m) picture elements is read out with a total of (n + m) amplifier and discriminator circuits is described. Results obtained with a breadboard (32 x 32)-element array employing 64 charge-sensitive amplifiers are presented, and the application of systems of this type in spectrometers and cameras for use with ground-based telescopes and on orbiting spacecraft discussed.
The log N-log S slope of optically identified galaxies in the 3CR catalog is analyzed for galaxies with flux levels greater than 10 Jy and located at galactic latitudes greater than 7 deg. For the 86 galaxies with known redshifts, the slope is found to be about 1.16; for all 119 galaxies, the slope is found to be about 1.50. If the 113 unidentified sources are included, the slope steepens to about 1.81. It is shown that this steepness is caused by the unidentified sources. Assuming that the slope is due to evolution at redshifts of 1 to 3 and that the unidentified sources are bright ellipticals, the mean redshifts and apparent brightnesses of these galaxies are calculated. The results indicate that it is impossible to observe the unidentified sources with existing ground-based telescopes, implying that it is presently impossible to establish directly that evolution is responsible for the steep log N-log S curve of the 3CR galaxies.
Recent advances in spectroscopic studies of the planets with ground-based telescopes in the photomultiplier and IR spectral ranges are reviewed. Results of spectroscopic observations of Venus and Mars are briefly summarized, noting that the crucial problem confronting the interpretation of the Venusian spectrum is the nature of the clouds and that the outstanding problem in understanding the Martian atmosphere is the N2 or Ar concentration that may be present. Spectroscopic results for Jupiter, Saturn, Uranus, and Neptune are discussed, emphasizing observations of molecular hydrogen, HD, water, (C-13)H4, other hydrocarbons, and deuterated hydrocarbons. IR and visual spectroscopic observations of Titan and Io are reviewed which show that the CH4 bands in Titan's spectrum are pressure broadened and that a flattened ring of sodium is situated around Jupiter in the orbital plane of Io.
An event compilation is presented which correlates ATM/S-056 X-ray event analyzer solar observations with solar flare activity. Approximately 1,070 h of pulse height analyzed X-ray proportional counter data were obtained with the X-ray event analyzer during Skylab. During its operation, 449 flares (including 343 flare peaks) were observed. Seventy events of peak X-ray emission or = Cl were simultaneously observed by ground based telescopes, SOLRAD 9 and/or Vela, and the X-ray event analyzer. These events were observed from preflare through flare rise to peak and through flare decline.
Data from high-resolution SEC vidicon spectroscopy with a ground-based telescope (for the Ca II K line) and from spectral scans made with the BUSS ultraviolet balloon spectrograph (for the Mg II h and k lines) are used to derive models of the chromospheres and upper photospheres of three G-K giants. The models are based on partial-redistribution analyses of the Ca II K line wings and cores and on the fluxes in the Mg II lines. The photospheres thus computed are hotter than predicted by radiative-equilibrium models. The minimum-to-effective temperature ratio is found to decrease with decreasing effective temperature, while the mass column density at the top of the chromosphere increases with decreasing stellar surface gravity. The computed pressure at the chromosphere top in the primary member of the Capella spectroscopic binary system is 70 times smaller than the transition-region pressure derived by Haisch and Linsky (1976), which suggests that additional terms must be included in the transition-region energy equations for giant stars. Estimates of the Ca II and hydrogen column densities are made for the circumstellar envelope of Aldebaran.
Infrared spectroscopic observations from NASA-operated aircraft constitute a rapidly maturing application of FTS methods initially developed for ground-based telescopes. Coupled to airborne telescopes up to 36 in. in diameter, these experiments are now producing new astronomical results as exciting and unexpected as those derived from Connes's first high resolution planetary observations at mountain-top observatories. This review examines the special problems of the IR spectral region that led to aircraft observatories and includes a brief survey of the facilities themselves and their modes of operation. The special problems of operating FTS devices on aircraft and the scientific results achieved with current capabilities are discussed. Finally, airborne observations are compared to the ultimate in high-altitude observing platforms: earth-orbiting cooled and uncooled telescopes carried by the Space Shuttle vehicle.
Jupiter's low-frequency radio emission were detected by the planetary radio astronomy instruments onboard the two Voyager spacecraft. The emission is surprisingly similar in morphology but opposite in polarization to the high-frequency Jovian radio noise that were observed with ground-based telescopes for more than two decades. Several possible explanations for the behavior of the low-frequency emission are examined, but none of them is completely satisfactory.
Images of the lunar surface are being obtained at several wavelengths using a silicon vidicon imaging system and ground-based telescopes. These images are recorded and processed in digital form so that quantitative information is preserved; their photometric precision has been shown to be 1% or better. Ratio images, calculated by dividing those obtained at two wavelengths (0.40/0.56 and 0.95/0.56 micron), were presented in an earlier article, and more are presented here for a total coverage of about 60% of the lunar frontside. Spatial resolution is about 2 km at the subearth point. A complex of distinct units is evident in the images. Earlier work with the reflectance spectrum of lunar materials indicates that for the most part these units are compositionally distinct. These digital images are being used by lunar geologists to interpret the history of the lunar surface.
The peculiar Be star HD 45677 was observed at low and high resolution by the IUE, and nearly simultaneous optical and IR observations were obtained with ground-based telescopes. These data were used to produce a spectral energy distribution extending from 0.12 to 12.6 microns in order to investigate the conversion of UV to IR radiation in the circumstellar dust shell. The high-resolution spectra indicate a spectral type of B2 in agreement with the optical classification.
In order to understand the nature of weathering processes and the formation of clay-like substances on Mars, analogous terrestrial processes and materials have been examined including sideromelane and palagonite. It is shown that palagonite is a good analog to the soil of Mars to the level of precision available from Viking and ground-based telescopic spectral measurements. Points of resemblance between the two materials include bulk chemical composition, particle size, reflectance spectra, and magnetic properties. A mechanism for the formation of Martian soil, based on a palagonite model, is proposed.
Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.
An infrared imaging photometer employing a monolithic 32 x 32 pixel bismuth doped silicon charge injection device array is described. The device is primarily useful in the 8-13-micron atmospheric window. The detector is sufficiently sensitive to provide good performance on ground-based telescopes and promises to be very good for low background space flight operation.