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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.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Solar response of the BATSE instrument on the gamma-ray observatory

The Burst and Transient Source Experiment (BATSE) on board the gamma ray observatory (GRO) aims at comprehensive observations of time profiles, spectra, and locations of high-energy transient sources. The mysterious cosmic gamma ray bursts provided the main motivation for the observations, but BATSE will make excellent observations of many classes of sources, and in particular solar flares. The solar response of BATSE, as inferred from its design parameters, is analyzed for two purposes: the optimization of the solar observations themselves, and the characterization of the solar effects on ordinary nonsolar observations.

Fishman, G. J.↗
NASA NTRS1999

Preview of the BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

The Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory (CGRO) has been detecting and monitoring point sources in the high energy sky since 1991. Although BATSE is best known for gamma ray bursts, it also monitors the sky for longer-lived sources of radiation. Using the Earth occultation technique to extract flux information, a catalog is being prepared of about 150 sources potential emission in the large area detectors (20-1000 keV). The catalog will contain light curves, representative spectra, and parametric data for black hole and neutron star binaries, active galaxies, and super-nova remnants. In this preview, we present light curves for persistent and transient sources, and also show examples of what type of information can be obtained from the BATSE Earth occultation database. Options for making the data easily accessible as an "on line" WWW document are being explored.

Harmon, B. A.↗
NASA NTRS2002

The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 1984), as well as new transient sources discovered with BATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling to about 175 objects. The catalog will present the global properties of these sources and their probability of detection (greater than 10 mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the High Energy Astrophysics Science Archive Research Center (HEASARC) for public use.

Harmon, B. A.↗
NASA NTRS2002

The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4, as well as new transient sources discovered with BATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique was used to monitor a combination of these sources, mostly galactic, totaling to about 175 objects. The catalog will present the global properties of these sources and their probability of detection (> 10 mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

Harmon, B. A.↗
NASA NTRS2004

The BATSE Earth Occultation Catalog of Low Energy Gamma-Ray Sources

The Burst and Transient Source Experiment (BATSE),aboard the COmptOn Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 19841, as well as new transient sources discovered with RATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling about 175 objects. The catalog will present the global properties of these sources and their probability of detection (>lO mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

Harmon, B. A.↗
DOE OSTI2023

Creating a High Energy Alert System for the HAWC Gamma Ray Observatory [Slides]

One of the greatest mysteries in astrophysics is exactly how Cosmic Rays (CRs) are accelerated up to extremely high energies within our galaxy. Hadronic models of possible CR accelerators, including supernova remnants and pulsars, require the production of both gamma rays and neutrinos at these sources. Searching for coincidences between neutrino and the highest energy gamma ray observations can help confirm these theories. The High Altitude Water Cherenkov (HAWC) observatory is a ground based gamma ray observatory located at 4100m in Puebla, Mexico. HAWC is able to detect gamma rays with energies greater than 100 TeV, has a wide field of view, and a 95% duty cycle, making it ideal for these types of coincidence searches. This work aims to create a high energy alert system for HAWC, sending out an alert to other experiments for gamma ray events it sees above 56 TeV.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1989

Monte Carlo models and analysis of galactic disk gamma-ray burst distributions

Gamma-ray bursts are transient astronomical phenomena which have no quiescent counterparts in any region of the electromagnetic spectrum. Although temporal and spectral properties indicate that these events are likely energetic, their unknown spatial distribution complicates astrophysical interpretation. Monte Carlo samples of gamma-ray burst sources are created which belong to Galactic disk populations. Spatial analysis techniques are used to compare these samples to the observed distribution. From this, both quantitative and qualitative conclusions are drawn concerning allowed luminosity and spatial distributions of the actual sample. Although the Burst and Transient Source Experiment (BATSE) experiment on Gamma Ray Observatory (GRO) will significantly improve knowledge of the gamma-ray burst source spatial characteristics within only a few months of launch, the analysis techniques described herein will not be superceded. Rather, they may be used with BATSE results to obtain detailed information about both the luminosity and spatial distributions of the sources.

Hakkila, Jon↗
NASA NTRS1992

HEAO 3 limits on the Ti-44 yield in Galactic supernovae

Data fron the high-resolution gamma-ray spectroscopy experiment on HEAO 3 have been searched for line emission from the decay of Ti-44 created in recent, as yet unobserved, Galactic supernova explosions, where the ages and locations are unknown. Because the 78 yr mean life of Ti-44 is comparable to the average time between Galactic supernovae, the gamma-ray line emission from its decay should appear as Galactic point sources. No evidence was found for such emission from a point source anywhere in the Galactic plane, with a 1-sigma limit of 8.3 x 10 exp -5 photons/sq cm per sec. Detailed models were developed to simulate the Galactic gamma-ray emission from the decay of Ti-44 produced in both type I and type II supernovae. These models were used with the measured gamma-ray line limits to constrain the supernova yields and recurrence periods.

Mahoney, W. A.↗
NASA NTRS1994

A review of recent results in gamma-ray astronomy obtained from high-altitude balloons

This paper reviews recent results in gamma-ray astronomy obtained from experiments flown on high-altitude balloons. New generation balloon-borne imaging experiments have produced the first gamma-ray maps of the Galactic center (GC) region. Balloon flights of new gamma-ray spectrometers with improved sensitivity have provided important new information on the GC annihilation line. For the first time, the narrow 511 keV line as been resolved (FWHM approx. = 3 keV). A very interesting spectral feature at approximately 170 keV has been attributed to backscattered annihilation, probably from the vicinity of a compact object. New results from the Compton Gamma-Ray Observatory (CGRO)/OSSE and Granat/SIGMA experiments on the annihilation line, when considered together with the recent balloon results, have added greatly to our knowledge and understanding of the origin and distribution of this emission. Balloon-borne instruments have made important measurements of gamma-ray continuum and line emission from SN 1987A. The GRIS spectrometer unambiguously resolved the 847 and 1238 keV line emission from radioactive Co-56 synthesized during the explosion. This data indicated that simple spherically symmetric and homogeneous models did not provide an adequate description of the expanding SN shell.

Teegarden, B. J.↗
NASA NTRS1991

Gamma ray astronomy

Miscellaneous tasks related to the development of the Burst and Transient Source Experiment on the Gamma Ray Observatory and to collection, analysis, and interpretation of data from the MSFC Very Low Frequency transient monitoring program were performed. The results are summarized and relevant references are included.

Paciesas, William S.↗
NASA NTRS1988

Gamma ray astrophysics to the year 2000. Report of the NASA Gamma Ray Program Working Group

Important developments in gamma-ray astrophysics up to energies of 100 GeV during the last decade are reviewed. Also, the report seeks to define the major current scientific goals of the field and proposes a vigorous program to pursue them, extending to the year 2000. The goals of gamma-ray astronomy include the study of gamma rays which provide the most direct means of studying many important problems in high energy astrophysics including explosive nucleosynthesis, accelerated particle interactions and sources, and high-energy processes around compact objects. The current research program in gamma-ray astronomy in the U.S. including the space program, balloon program and foreign programs in gamma-ray astronomy is described. The high priority recommendations for future study include an Explorer-class high resolution gamma-ray spectroscopy mission and a Get Away Special cannister (GAS-can) or Scout class multiwavelength experiment for the study of gamma-ray bursts. Continuing programs include an extended Gamma Ray Observatory mission, continuation of the vigorous program of balloon observations of the nearby Supernova 1987A, augmentation of the balloon program to provide for new instruments and rapid scientific results, and continuation of support for theoretical research. Long term recommendations include new space missions using advanced detectors to better study gamma-ray sources, the development of these detectors, continued study for the assembly of large detectors in space, collaboration with the gamma-ray astronomy missions initiated by other countries, and consideration of the Space Station attached payloads for gamma-ray experiments.

Source record↗
NASA NTRS1991

HEAO 3 observations of strong variable 0.5-3 MeV emission from the Taurus region

Preliminary results are reported of observations of strong (greater than 10 sigma) variable MeV emission from the Taurus region, possibly the Crab nebula, in 1980 by the HEAO 3 Gamma-Ray Spectroscopy experiment. The about 50-day time-averaged spectrum of the Crab shows a new component, which consists of a hard spectral 'knee' in the 0.4-1 MeV range, followed by a higher energy component extending to greater than 3 MeV, superposed on the canonical Crab power law spectrum with a spectral index of 2.2. This new spectral component was not observed four months earlier in the fall of 1979, when the spectrum was consistent with a single power law with the index of 2.2, the same as that observed in 1980. There is no indication that the gamma-ray emission was pulsed.

Ling, James C.↗
NASA NTRS2003

The Mars Underground Mole (MUM): A Subsurface Penetration Device with Infrared Reflectance and Raman Spectroscopic Sensing Capability

Searching for evidence of life on Mars will probably require access to the subsurface. The Martian surface is bathed in ultraviolet radiation which decomposes organic compounds, destroying possible evidence for life. Also, experiments performed by the Viking Landers imply the presence of several strongly oxidizing compounds at the Martian surface that may also play a role in destroying organic compounds near the surface. While liquid water is unstable on the Martian surface, and ice is unstable at the surface at low latitudes, recent results from the Mars Odyssey Gamma Ray Spectrometer experiment indicate that water ice is widely distributed near the surface under a thin cover of dry soil. Organic compounds created by an ancient Martian biosphere might be preserved in such ice-rich layers. Furthermore, accessing the subsurface provides a way to identify unique stratigraphy such as small-scale layering associated with lacustrine sediments. Subsurface access might also provide new insights into the Mars climate record that may be preserved in the Polar Layered Deposits. Recognizing the importance of accessing the subsurface of Mars to the future scientific exploration of the planet, the Mars Surveyor 2007 Science Definition Team called for drilling beneath the surface soils. Subsurface measurements are also cited as high priority in by MEPAG. Recognizing the importance of accessing the Martian subsurface to search for life, the European Space Agency has incorporated a small automated burrowing device called a subsurface penetrometer or Mole onto the Beagle 2 lander planned for 2003 launch. This device, called the Planetary Underground Tool (PLUTO), is a pointed slender cylinder 2 cm wide and 28 cm long equipped with a small sampling device at the pointed end that collects samples and brings them to the surface for analysis. Drawing on the PLUTO design, we are developing a larger Mole carrying sensors for identifying mineralogy, organic compounds, and water.

Stoker, C. R.↗
NASA NTRS1999

A Counterpart Search for a Source of 2.2 MeV Gamma-Rays

The goal of this project was to search for a counterpart to an apparent point source of 2.2 MeV gamma-rays that had been detected using data from the COMPTEL experiment on Compton Gamma Ray Observatory (CGRO). The source detected by Compton Telescope (COMPTEL) was of marginal significance (less than 4 sigma) and a further confirmation at low energies was highly desired. An observation of this region was Rossi X Ray Timing Explorer (RXTE) performed on 04-Feb-1998. An analysis of the Proportional Counter Array (PCA) data from this observation yielded a negative result. Short discussions of the COMPTEL Source, RXTE Observations, RXTE Analysis results, other observations as well as future work are included.

McConnell, Mark L.↗
NASA NTRS1979

HEAO 1 observations of high-energy X-rays from 3C273

The first detection of high energy (13 to 120 keV) X rays from the quasar 3C273, made by the HEAO 1 satellite, is reported. Observations were made with the 13 to 180 keV slat collimated detectors of the high energy X-ray and low energy gamma-ray (A4) experiment during December 1977-January 1978 and June-July 1978. Results are consistent with the previously observed X-ray flux variability on a scale of months. Photon count rates are presented for each of five energy bands and count rate and photon spectra for the June through July 1978 observations are derived. A comparison of the data obtained with that at lower X-ray energies and higher gamma-ray energies indicates that there is an overall spectral steepening from low to high energies and a possible break near 20 keV, which may be due to the gamma rays originating from a different region than that of the X rays.

Primini, F. A.↗
NASA NTRS1985

An EAS experiment at mountain altitude for the detection of gamma-ray sources

The plan of an extensive air shower experiment 2.200 m above sea level for the detection of 10 to the 14th power eV to 10 to the 17th power eV gamma rays from sources in the declination band 0 deg to + 60 deg is described. The site selection, detector array and electronic layout are detailed.

Allkofer, O. C.↗
NASA NTRS1994

The first BATSE gamma-ray burst catalog

The Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory detected 260 cosmic gamma-ray bursts during the period 19 Apr 1991 to 5 Mar 1992. This paper presents the occurrence times, locations, peak count rates, peak fluxes, fluences, durations, and plots of time histories for these bursts. The angular distribution is consistent with isotropy. The intensity distribution shows a deficit in the number of weak bursts, which is not consistent with a homogeneous distribution of burst sources in Euclidean space. The duration distribution shows evidence for a separate class of bursts with durations less than about 2 seconds.

Fishman, Gerald J.↗