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At least 1,045 records · Page 58

Spectral response of the Viking lander camera: Preliminary evaluation

One of the objectives of the Viking lander imaging investigation is to obtain color and near-infrared multispectral panoramas of the Martian surface using six spectral channels in the 0.4 to 1.1 microns wavelength range. This data can be compared with data obtained by imaging a reference test chart to construct approximate spectral reflectance curves that can then be matched to laboratory standards to aid in identifying surface materials. Some channels exhibit appreciable out-of-band spectral responses, making data reduction and interpretation difficult. A preliminary evaluation of predicted multispectral data for eight geological materials reveals that fairly good reflectance estimates can be made for those materials which have monotonically increasing or decreasing reflectances. Reflectance estimates for materials with more complex reflectances often do not reveal important spectral features and sometimes provide misleading results.

Kelly, W. L., IV↗

Analytic aerotriangulation utilizing Skylab earth terrain camera (S-190B) photography

The author has identified the following significant results. Inherent errors in using nonmetric Skylab photography and office-identified photo control made it necessary to perform numerous block adjustment solutions involving different combinations of control and weights. The final block adjustment was executed holding to 14 of the office-identified photo control points. Solution accuracy was evaluated by comparing the analytically computed ground positions of the withheld photo control points with their known ground positions and also by determining the standard errors of these points from variance values. A horizontal position RMS error of 15 meters was attained. The maximum observed error in position at a control point was 25 meters.

Keller, M.↗

A global station coordinate solution based upon camera and laser data - GSFC 1973

The results of a determination of the coordinates of about 70 tracking stations are presented. The data were deived with the aid of dynamical techniques from precise reduced optical and laser observations of geodetic satellites. It is attempted to establish a reasonable accuracy estimate through a comparison of the data with other independent solutions. A brief description is given of the independent solutions used as a source of comparison.

Marsh, J. G.↗

Temporal X-ray astronomy with a pinhole camera

Preliminary results from the Ariel-5 All-Sky X-Ray Monitor are presented, along with sufficient experiment details to define the experiment sensitivity. Periodic modulation of the X-ray emission is investigated from three sources with which specific periods have been associated, with the results that the 4.8 h variation from Cyg X-3 is confirmed, a long-term average 5.6 day variation from Cyg X-1 is discovered, and no detectable 0.787 day modulation of Sco X-1 is observed. Consistency of the long-term Sco X-1 emission with a 'shot-noise' model is discussed, wherein the source behavior is shown to be interpretable as about 100 'flares' per day, each with a duration of several hours. A sudden increase in the Cyg X-1 intensity by almost a factor of three on 22 April 1975 is reported, after 5 months of relative source constancy. The light curve of a bright nova-like transient source in Triangulum is presented, and compared with previously observed transient sources. Preliminary evidence for the existence of X-ray 'bursts' with duration less than 1 h is offered, with the caveat that there is not yet any supporting evidence to guarantee that the effect is truly astronomical.

Holt, S. S.↗

Subsurface "radar" camera

Long-wave length multiple-frequency radar is used for imaging and determining depth of subsurface stratified layers. Very-low frequency radar signals pinpoint below-ground strata via direct imagery techniques. Variation of frequency and scanning angle adjusts image depth and width.

Jain, A.↗

Phobos transit of Mars as viewed by the Viking cameras

A Viking orbiting spacecraft successfully obtained pictures of the martian satellite Phobos with Mars in the background. This is the first time that a single picture was obtained from a spacecraft which contained both a planet and a moon and had significant surface detail visible on both. The region of Mars below Phobos included volcanoes in the Tharsis Montes region. These pictures showed Phobos to be smaller than previously thought. The image of Phobos can be used as a control point to determine the map coordinates of surface features on Mars.

Duxbury, T. C.↗

Magnetic spring in oscillating mirror linear scanner for satellite camera

One of the main difficulties encountered in the development of a multispectral scanner is the realization of an oscillating mechanical device. A magnetic device which is characterized by the absence of friction is presented. The main developments concern the analysis of magnetic forces. A preliminary project of a device which could be used in a satellite is presented.

Thomin, G.↗

Sealed position sensitive hard X-ray detector having large drift region for all sky camera with high angular resolution

A sealed position sensitive proportional counter filled with two atmospheres of 95% xenon and 5% methane, and containing a drift region of 24 atm cm, has operated in a stable manner for many months. The detector contains G-10 frames to support the anode and cathode wires. The detector was sealed successfully by a combination of vacuum baking the G-10 frames at 150 C for two weeks followed by assembly into the detector in an environment of dry nitrogen, and the use of passive internal getters. The counter is intended for use with a circumferential cylindrical collimator. Together they provide a very broad field of view detection system with the ability to locate cosmic hard X-ray and soft gamma ray sources to an angular precision of a minute of arc. A set of instruments based on this principle have been proposed for satellites to detect and precisely locate cosmic gamma ray bursts.

Gorenstein, P.↗

Mare Crisium area topography - A comparison of earth-based radar and Apollo mapping camera results

An earth-based radar topography (ERT) map has been constructed of the Mare Crisium area. Systematic and random sources of error are discussed. A comparison between the ERT map and Lunar Topographic Orthophotomaps shows a random mean discrepancy of less than 100 m between the two maps, except for small-scale (20 km or less in diameter) features, where systematic smoothing reduces the ERT elevation contrast

Zisk, S.↗

Wide-field electrographic cameras for imagery and spectrography at visual and middle-UV wavelengths

The use of a Kron electrographic detector for wide-field, narrow-band imagery of faint emission nebulosity in the near-UV and visual (3100-6000 A) wavelength interval is described. As an example of the photometric quality of the imagery and of the sensitivity of the instrumentation to diffuse, low-contrast objects, imagery of the Cygnus Loop supernova remnant in the high excitation forbidden line of Ne V 3426 A is presented. In addition, a program to develop electrographic detectors which use cesium telluride photocathodes for broad-band imagery and spectrography in the middle-UV (1650-3100 A) wavelength range is described.

Heckathorn, H. M.↗

Field-widened pinhole camera

Wood demonstrated a method in 1906 that allowed 180-deg FOV but required that the film be immersed in a tank of water. This paper presents a technique that yields the same 180-deg FOV without the necessity of wetting the film. Rays from a 180-deg FOV cone are reduced to 84-deg cone due to refraction at the glass surface. If the cone were then incident on another glass/air plane surface, it would be expanded back to 180 deg.

Franke, J. M.↗