An optical search for the X-ray sources GX3 plus 1, GX5-1, GX9 plus 1, and GX17 plus 2
X ray sources identification with optical counterparts, noting lack of radio and pulsar type emissions
Bradt, H.↗
SEARCH · Search NASA
Results for “optical sources”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Hazards from High Intensity Lamps and Arcs
The principal occupational health problem generally associated with high intensity arc lamps results from exposure of the eye and skin to ultraviolet radiation. Occasionally, the chorioretinal burns are of concern. The eye is generally more susceptible than the skin to injury from high intensity optical radiation sources whether ultraviolet, visible or infrared. Recent developments in technology have shown that some high intensity optical radiation sources which have output parameters greatly different from those encountered in the natural environment present a serious chorioretinal burn hazard.
Sliney, D. H.↗
Optical detector calibrator system
An optical detector calibrator system simulates a source of optical radiation to which a detector to be calibrated is responsive. A light source selected to emit radiation in a range of wavelengths corresponding to the spectral signature of the source is disposed within a housing containing a microprocessor for controlling the light source and other system elements. An adjustable iris and a multiple aperture filter wheel are provided for controlling the intensity of radiation emitted from the housing by the light source to adjust the simulated distance between the light source and the detector to be calibrated. The geared iris has an aperture whose size is adjustable by means of a first stepper motor controlled by the microprocessor. The multiple aperture filter wheel contains neutral density filters of different attenuation levels which are selectively positioned in the path of the emitted radiation by a second stepper motor that is also controlled by the microprocessor. An operator can select a number of detector tests including range, maximum and minimum sensitivity, and basic functionality. During the range test, the geared iris and filter wheel are repeatedly adjusted by the microprocessor as necessary to simulate an incrementally increasing simulated source distance. A light source calibration subsystem is incorporated in the system which insures that the intensity of the light source is maintained at a constant level over time.
Strobel, James P.↗
Subaru/HSC deep optical imaging of infrared sources in the AKARI North Ecliptic Pole-Wide field
In this work, we present a five-broad-band (grizy) photometric catalogue of Subaru/Hyper Suprime-Cam (HSC) optical imaging observations at around the North Ecliptic Pole (NEP) where the AKARI infrared (IR) satellite conducted a large survey (NEP-Wide survey). The observations cover almost all the NEP-Wide survey field down to the depth of 28.1, 26.8, 26.3, 25.5, and 25.0 mag (5σ) at grizy, respectively. The five-band HSC catalogue contains about 2.6 million objects, and 70 959 AKARI NEP-Wide counterpart sources are identified in the catalogue. We added existing supplementary catalogues from the u band to the far-IR band, and estimated photo-z for the AKARI-HSC sources. We achieved σΔz/(1 + zs) = 0.06 and an outlier rate of 13.4 per cent at z = 0.2–1.5. Using the spectral energy distribution (SED) template fitting, we classified the AKARI-HSC galaxies into four categories, namely quiescent, star-forming, Type1 active galactic nucleus (AGN), and Type2 AGN, in each redshift bin. Then, at z > 1, the mean SED of star-forming galaxies in mid-IR (3–10 μm) range is significantly different from that of spiral galaxies in the nearby Universe, indicating that many of star-forming galaxies at z > 1 contain a heat source capable of heating dust to temperatures that radiate thermal emission in the mid-IR range. Furthermore, we estimated the number fraction of AGNs (fAGN) in each bin of redshift and IR luminosity (L IR ), and examined the dependence of redshift and L IR . In log(L IR /L ⊙ ) = 11.0–14.0, the fAGN shows a significant increase with increasing redshift, regardless of the LIR bins. In contrast, the fAGN shows a slight increase against L IR at z < 1 and no increase with increasing L IR at z > 1.
79 ASTRONOMY AND ASTROPHYSICS↗
Effects of error sources on the parallelism of an optical matrix-vector processor
The error sources in a high accuracy optical matrix-vector processor are analyzed by numerical simulation in terms of their effects on the parallelism and speed of the processor. These effects are detailed for radices -2, -4 and -8. Radix -4 is shown to provide maximum parallel processing capabilities under the effects of the system's error sources. Processing speed is shown to be a function of matrix partitioning and the number of parallel processing channels. Consequently, radix -4 operation provides a higher processing speed than radix -2 and -8 for most matrix-vector multiplications when error source effects are considered.
Perlee, Caroline J.↗
OTS 1809+314 and the gamma-ray burst GB 790325b
Deep CCD images of the field containing the recurring Optical Transient Source (OTS) 1809+314 recently discovered on archival plates of the Sonneberg Observatory are presented. At the position of OTS 1809+314 no optical counterpart brighter than V = 24.0-24.5, r(Gunn) = 22.0-22.5, and I = 22.0-22.5 is found. In the zero proper motion limit our observations place severe constraints on possible quiescent counterparts. There is no compelling evidence to suggest an association between the historical optical transient source and the gamma-ray burst GB 790325b located about 5 arcmin to the east of OTS 1809+314.
Hartmann, Dieter↗
Mariner-Venus-Mercury optical navigation demonstration - Results and implications for future missions
Optical navigation uses spacecraft television pictures of a target body against a known star background in a process which relates the spacecraft trajectory to the target body. This technology was used in the Mariner-Venus-Mercury mission, with the optical data processed in near-real-time, simulating a mission critical environment. Optical data error sources were identified, and a star location error analysis was carried out. Several methods for selecting limb crossing coordinates were used, and a limb smear compensation was introduced. Omission of planetary aberration corrections was the source of large optical residuals.
Acton, C. H., Jr.↗
Physical optics simulations for synchrotron radiation sources
Here we describe approaches to high-accuracy physical optics calculations used for the development of x-ray beamlines at synchrotron radiation sources, as well as simulation of experiments and processing of experimental data at some of these beamlines. We pay special attention to the treatment of the partial coherence of x rays, a topic of high practical importance for modern low-emittance high-brightness synchrotron radiation facilities. The approaches are based, to a large extent, on the works of Emil Wolf and co-authors, including the basic scalar diffraction theory and the coherent mode decomposition method. The presented simulation examples are related to the case of the novel Coherent Diffractive Imaging beamline that is currently under development at the National Synchrotron Light Source II at the Brookhaven National Laboratory.
36 MATERIALS SCIENCE↗
Transversely polarized source cladding for an optical fiber
An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented transversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.
Egalon, Claudio Oliveira↗
Perceiving environmental structure from optical motion
Generally speaking, one of the most important sources of optical information about environmental structure is known to be the deforming optical patterns produced by the movements of the observer (pilot) or environmental objects. As an observer moves through a rigid environment, the projected optical patterns of environmental objects are systematically transformed according to their orientations and positions in 3D space relative to those of the observer. The detailed characteristics of these deforming optical patterns carry information about the 3D structure of the objects and about their locations and orientations relative to those of the observer. The specific geometrical properties of moving images that may constitute visually detected information about the shapes and locations of environmental objects is examined.
Lappin, Joseph S.↗
The microwave brightness temperature spectrum of the quiet sun
New measurements of the microwave brightness temperature spectrum of the center of the quiet sun, acquired at Owens Valley over several months during the 1986-1987 sunspot minimum, are reported. The resulting brightness temperature spectra are consistent with previous data, but exhibit much less frequency-to-frequency scatter. The corona is fitted well by an optically thin source at temperature of 10 to the 6th k, scale height H = 5 x 10 to the 9th, and density of 3.2 x 10 to the 8th/cu cm, and the chromosphere, an optically thick source at around 11,000 k.
Zirin, H.↗
Possible optical counterparts to the X-ray point source in the supernova remnant CTB 80
A three color CCD image of the central region of the supernova remnant CTB 80 is presented, along with astrometry and photometry of many stars in the field. The color image does not show evidence of heavy or variable dust absorption in the surrounding region. Using an Einstein High Resolution Imager position for the central X-ray point source, two possible optical counterparts have been identified at magnitudes V = 19.9 and V = 20.9. Comparison of the intrinsic colors and magnitudes of these candidates are made to the optical properties of Crab and Vela pulsars, and they are found to be viable candidates.
Blair, W. P.↗
Towards a new generation long trace profiler LTP-2020: optical design of pencil beam interferometry sensor
Improvements in the quality of synchrotron beamline x-ray optics required for next-generation light sources (e.g. the ALS Upgrade project) drive the need to improve the performance of the metrology instrumentation used to measure these components. The Long Trace Profiler (LTP) that is in use at many synchrotron metrology laboratories around the world has some known issues that affect the accuracy of its measurements. The main error source is optical path difference (OPD) phase error introduced into the probe beam by inhomogeneities in the glass components used in the optical head. We have developed a new optical head design, LTP-2020, that replaces the cube polarizing beamsplitter (PBS) with a thin wedge plate polarizing beamsplitter (WPBS) and replaces the cemented doublet lens with an aspheric singlet. Both of these components significantly reduce the glass volume traversed by the laser probe beam. Careful attention to ghost ray interference produced by back reflection from optical surfaces is necessary to minimize distortion in the primary image that translates into systematic error in the slope angle measurement. We make extensive use of a commercial raytracing program to model the back reflections and adjust component parameters as necessary to minimize distortion. Deliberate misalignment of components is necessary to make the system perform correctly. Stringent requirements are placed on the 45◦ incidence coatings on the WPBS and on the normal incidence coatings on the lens and camera window elements. We encourage our colleagues who wish to upgrade their current LTP systems to join us in the procurement of these custom optical components.
Takacs, Peter Z.↗
Photometry of AM Herculis - A slow optical pulsar
Multicolor photometry of the X-ray binary AM Her suggests that the red component of the optical flux is closely related to the source of optical circular polarization in the system. It is concluded from the periodic modulation of flux in the U through R bands, which is particularly well-defined when plotted as color curves, that the primary and secondary minima are neither eclipses by a secondary star nor eclipses by a hot spot. It is suggested that the primary minimum in the visual light curve is the eclipse of a region of intense optical emission in the magnetic field near the surface of a degenerate dwarf by that dwarf itself.
Priedhorsky, W. C.↗
Optical multiple sample vacuum integrating sphere
An integrating sphere comprised of a uniform difusely reflecting spherical cavity, having mutually transverse input and output ports, and a linear sample transport mechanism is described. The sample transport mechanism is secured so that the multiple samples can be brought into registration with the input port, one at a time, without having to open or disassemble the apparatus when a change of sample is desired. A vacuum tight seal is provided between the cavity and the transport mechanism. This maintains the integrity of a vacuum generated with the sphere when attached to the source of optical energy. The device is utilized to test emissive characteristics such as the relative fluorescence quantum efficiency of a dye sample placed in the path of a monochromatic optical energy source coupled to the input port while having a light detector coupled to the output port.
Butner, C. L.↗
Proposal for a conceptually new compact collecting optics for powerful light sources
Testing of a spacecraft under simulated outer space conditions is the best guarantee for a successful mission, and for almost all of the parameters a good match (to within a few percent) may be reached in relevant test facilities (e.g., IR background, earthshine and albedo radiation, residual atmosphere, intensity stability, distribution and spectrum of the solar radiation). The collimation angle of the sun (32 arc min) is, however, a drastic exception, here only + or - 1.5 to 2 deg are achieved which means a relative deviation by nearly one order of magnitude. The main reason for this is the presently used collecting optics having unnecessary large diameters. Here a lens-mirror combination is proposed which allows the reduction of the diameter by nearly a factor of two and to achieve with the present Xenon arc lamps a collimation angle of + or - 0.8 deg.
Saenger, G.↗
Design of Hypervelocity Flow Generator (HFG) and Its Diagnostics
Ground facilities for hypersonic research are a key element for successful development of aerodynamically proven hypervelocity vehicles. Design concepts and diagnostics of a hypervelocity flow generator (HFG) were made as a test platform for hypersonic/hypervelocity spacecraft models at the NASA Langley Research Center. The HFG is a hypersonic flow field generator using optically heated gas which is blown into an 80 cu m vacuum chamber. The vacuum chamber is kept at a stable vacuum pressure with a combination of three large vacuum pumps, while the HFG is in the test mode. The HFG provides a relatively small test section with approximately a 20 cm window. This facility was designed to generate 2.45 km/sec of flow speed, and potentially generate a continuous flow with the nozzle and vacuum system. The window in test section provides a direct view of the shock wave around a model in order to measure temperature, pressure, and density profile within the shock layer. One of the key test goals under this project is to understand why the emission spectra from the standing shockwave plasma predicted by Lora-Loran codes are significantly different from the measured emission spectra from the Flight Investigation Reentry Environment (FIRE II) Flight. The correct estimate of the thermal loading on the leading edge of hypersonic vehicles greatly affects the aerodynamic design, the material selection for the vehicle, and the cooling requirement and can be obtained by the precise modeling of emission spectra from shockwave plasma. However, the estimation of thermal loading is not an easy task due to complex non-equilibrium radiative process within high temperature shock layers that still falls into a category of cold plasma. Direct flight experiments are the most desirable, but not a cost-effective approach. Analysis by computational fluid dynamics (CFD) offers many test flexibilities. However, the CFD codes must be fully tested and validated with experimental data before the codes are effectively used for practical design. Large discrepancies between experiments and codes appear in hypersonic/hypervelocity flow regimes at high altitudes of 60 km ~ 90 km. This HFG facility offers some important parameters for CFD code validation, such as collision cross-sections, relaxation times, reaction rate coefficients and transportation coefficients. The HFG test facility is based on the ejection flow of high temperature gas heated over to 3500 K through a nozzle. The tungsten gas chamber of the HFG is heated up to a desired temperature by a 60 kW optical power beam source. This system consists of an optical power source, a thermal chamber, an expansion nozzle, a test section, and an 80 cu m vacuum tank. 60 kW optical input power is obtained from the 150 kW Vortek arc lamp system (by Vortek Industries, Vancouver, Canada). This optical beam is focused to heat the gas chamber within which a flow media is heated. The maximum achievable temperature of the flow medium reached approximately 3500 K or even higher but is limited by the melting point of the chamber material used. The exhaust velocity through the nozzle was determined by the stagnation temperature and the molecular weight of the working medium at the test section. To provide design parameters, a NASA Chemical Equilibrium with Application (CEA) computer program is used for the simulation of aerothermal data. This CEA program can calculate chemical equilibrium and properties of complex mixtures using shock tube parameters. For nitrogen gas at 2666 K stagnation temperature, the maximum achievable velocity at the test section is approximately 2.45 km/sec which is within the range of the thermal velocity of 8000 K shock layer. Based on the calculation through the CEA program, the design parameters of a HFG were determined and implemented for the test section that includes an expansion nozzle. The installed test section of the experimental facility can sustain a condition of a re-entry vehicle from the Space at an altitude of 60-90 km. After installation of the HFG, the system was fully tested and its operational parameters were measured. An 80 cu m vacuum chamber of HFG was set at 1 torr level to keep a stable downstream condition. The pumping time to reach the minimum vacuum pressure (~ 1 torr) at the test chamber from atmospheric pressure was approximately an hour using Kinney (MBV-14000/MB -1600/KT-300) and Stokes (Model 1772 and 412) pumps. Such a setup condition allowed a continued stable operation of the HFG experiment with flowrates through 1-, 3-, or 5-mm diameters of nozzle throat. The flow characteristics of the HFG for various operating conditions were performed using a focused Schlieren method. At 0.8 torr chamber pressure, a barrel shock was observed at the test section. With a sphere obstacle of 12 mm diameter in the flow, a bow shock (~ 2-mm thickness) was observed by a focused Schlieren visualization method.
Hypervelocity flow↗
Variations in the optical spectrum of the quasi-stellar radio source 3C 345.
Variations in optical spectrum of quasi-stellar radio source 3C 345
ASTRONOMICAL SPECTRUM↗