| Gamma Ray Observations of Cygnus X-1 With the Oriented Scintillation Spectrometer Experiment |
1996 |
28 pages |
| Authors:
B. F. Phlips; G. V. Jung; M. D. Leising; J. E. Grove; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; M. S. Strickman; D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; K. McNaron-Brown; UNIVERSITIES SPACE RESEARCH ASSOCIATION WASHINGTON DC
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 | We report on ~120 days of observations of Cygnus X-1 with OSSE onboard the Compton Observatory. Emission is detected in the range 50 keV to 1 MeV and we find evidence for a continuum of hard X-ray flux levels rather than the existence of distinct flux states. Comparisons of the source spectra with various theoretical models show that an exponentially truncated power law best describes the average spectrum in the ... |
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| OSSE Observations of the Vela and Geminga Pulsars |
1996 |
24 pages |
| Authors:
M. S. Strickman; J. E. Grove; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
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| The Oriented Scintillation Spectrometer Experiment (OSSE) on board the Compton Gamma Ray Observatory detected the Vela Pulsar (PSR B0833-45) during August-September 1991, April-May 1992, and August 1993. Observed light curves have a two-peak pulse profile similar to that observed at higher energies, although the second peak may be wider in the OSSE light curve. Pulsed emission in the first gamma-ray peak was detected with 4.6 sigma statistical significance in the ... |
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| Gamma Ray Observations of Cygnus X-1 With OSSE |
1996 |
5 pages |
| Authors:
B. F. Phlips; G. V. Jung; M. D. Leising; J. E. Grove; W. N. Johnson; R. L. Kinser; R. A. Kroeger; J. D. Kurfess; M. S. Strickman; D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; K. McNaron-Brown; NAVAL RESEARCH LAB WASHINGTON DC
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| We report on ~120 days of observations of Cygnus X-1 with OSSE onboard the Compton Observatory. Emission is detected in the range 50 keV to 1 MeV and we find evidence for a continuum of hard X-ray spectra over a broad range of fluxes rather than the existence of distinct flux states. Comparisons of the source spectra with various theoretical models show that an exponentially truncated power law best describes ... |
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| OSSE Observations of 1E 1740.7=2942 in 1992 September |
11 JAN 1995 |
5 pages |
| Authors:
G. V. Jung; J. D. Kurfess; W. N. Johnson; R. L. Kinzer; J. E. Grove; M. S. Strickman; W. R. Purcell; D. A. Grabelsky; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC
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| We present data on the galactic X-ray source 1E 1740.7-2942 from the Oriented Scintillation Spectrometer Experiment (OSSE) on board NASA's Compton Gamma Ray Observatory. Episodes of increased low- energy gamma radiation have been reported from this source, including 1-day events in 1990 October and 1992 September. These events, of intensity 7 x 10(exp -3) and 4 x 10(exp -3) photons cm(exp-2) s(exp -1), respectively, have been interpreted as broadened and ... |
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| A Search for Fast Gamma Ray Pulsars with OSSE |
1995 |
28 pages |
| Authors:
P. Hertz; J. E. Grove; D. A. Grabelsky; S. M. Matz; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| Pulsar mode data from the Oriented Scintillation Spectrometer Experiment (OSSE) onboard the Compton Gamma Ray Observatory, with time resolution between 125 microsecond and 8 ms, have been analyzed for the presence of short period gamma-ray pulsations. Observations of known point sources (including SN 1987A, SN 1993J, GRO J0422+32, and several pulsars) and of regions where high densities of pulsars are expected (including the Galactic Center, the Galactic plane and arms, ... |
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| OSSE Observations of Blazars |
1995 |
25 pages |
| Authors:
K. McNaron-Brown; W. N. Johnson; G. V. Jung; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; C. D. Dermer; D. A. Grabelsky; W. R. Pucell; M. P. Ulmer; M. Kafatos; P. A. Becker; R. Staubert; M. Maisack; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| Results are reported on observations obtained with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory (CGRO) of 17 active galactic nuclei known to exhibit blazar properties at other wavelengths. These observations span the period from 1991 June through 1994 May. Of the 33 high-confidence EGRET detections of blazars during CGRO observing phases 1 and 2 (1991 May 16 - 1993 Sept. 7), OSSE has observed ... |
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| OSSE Observations of 3C 273 |
1995 |
19 pages |
| Authors:
W. N. Johnson; C. D. Dermer; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; K. McNaron-Brown; E. Jourdain; G. V. Jung; D. A. Grabelsky; W. R. Purcell; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| We report results of multiple observations of the quasar 3C 273 with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory. These observations span the period from 1991 June through 1993 January and represent the most sensitive observations to date in low-energy gamma rays. The source was detected at historically weak 100 keV fluxes compared with previous measurements. Variability by factors of ~ 3 on time ... |
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| Compton Observatory OSSE Studies of Supernovae and Novae |
1995 |
11 pages |
| Authors:
M. D. Leising; D. D. Clayton; L.-S. The; W. N. Johnson; J. D. Kurfess; R. L. Kinzer; R. A. Kroeger; M. S. Strickman; J. E. Grove; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; R. A. Cameron; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
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| A primary objective of the Compton Observatory is the direct study of explosive nucleosynthesis in supernovae and classical novae. We have been fortunate in that three rare events have coincided, relatively speaking, with the Compton Observatory launch. Supernova 1987A, roughly a once per century event, was only 4 years old at launch and so the gamma-ray flux from 57Co decay was not much past its peak value. Supernova 1991T, a ... |
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| OSSE Observations of GX 339-4 |
1995 |
20 pages |
| Authors:
D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; J. E. Grove; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
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| The Oriented Scintillation Spectrometer Experiment on the Compton Gamma Ray Observatory observed the Galactic black hole candidate GX 339-4 as a target of opportunity in 1991 September, in response to the outburst reported by BATSE. We report here on energy spectra in the 50 keV to 10 MeV range obtained by OSSE. The source was detected from 50 to 400 keV at a level relative to the Crab nebula of ... |
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| Compton Observatory OSSE Observations of Supernova 1991T |
1995 |
13 pages |
| Authors:
M. D. Leising; W. N. Johnson; J. D. Kurfess; D. D. Clayton; D. A. Grabelsky; G. V. Jung; R. L. Kinzer; W. R. Purcell; M. S. Strickman; L. S. The; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| The Oriented Scintillation Spectrometer Experiment on the Compton Observatory observed SN 1991T on three occasions in 1991. We find no evidence for 56Co gamma-ray line emission from SN 1991T in any of the three observations. Combining these measurements yields a 99% confidence upper limit of 4.1-6.6 x 10(exp -5) photons cu cm s(exp -1), depending on how the multiple observations are combined, for the 847 keV line flux in the ... |
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| OSSE Upper Limits to Pulsar Gamma-Ray Emission |
30 SEP 1994 |
28 pages |
| Authors:
P. C. Schroeder; M. P. Ulmer; S. M. Matz; D. A. Grabelsky; W. R. Purcell; J. E. Grove; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
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| We present upper limits from CGRO Oriented Scintillation Spectrometer Experiment (OSSE) observations of pulsars and a summary of pulsar observations made with the Compton Gamma-Ray Observatory (CGRO). We also report an upper limit to phase-averaged emission for the globular cluster 47 Tuc which is thought to contain many millisecond pulsars. The 2sigma upper limit is 3 x 10(exp -5) photons sq cm s(exp-1) keV(exp-1) in the 50-150 keV energy range. ... |
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| OSSE Observations of Centaurus A Over 18 Months |
1994 |
6 pages |
| Authors:
R. L. Kinzer; W. N. Johnson; J. D. Kurfess; M. S. Strickman; J. E. Grove; R. A. Kroeger; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| OSSE observed Centaurus A at energies between 0.05 and 10 MeV in 1991, 1992, and in 1993. During each observation, this AGN was found to be at relatively low intensities compared to previous observations. It exhibited roughly constant average intensity intervals of a few (5 to 8) days with abrupt (12 to 24-hour) intensity changes about the mean of as much as 60%. The spectral shape at low intensities can ... |
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| Estimating Starburst Supernova Rates Using OSSE Observations M82 and NGC 253 |
1994 |
7 pages |
| Authors:
D. Bhattacharya; L. -S. The; J. D. Kurfess; D. D. Clayton; N. Gehrels; D. A. Grabelsky; W. N. Johnson; G. V. Jung; R. L. Kinzer; M. D. Leising; W. R. Purcell; M. S. Strickman; M. P. Ulmer; CALIFORNIA UNIV RIVERSIDE INST OF GEOPHYSICS AND PLANETARY PHYSICS
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| We have used the OSSE observations of the starburst galaxies NGC 253 and M82 to obtain upper limits to the Type Ia and Ib supernova rates in these galaxies. Monte Carlo simulations of randomly occurring supernova events in NGC 253 and M82 were performed to evaluate the significance of our upper limit to the 0.847 and 1.238 MeV 56Co gamma-ray line fluxes on the supernova rate from these two galaxies. ... |
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| Hard X-Ray Variability of Cygnus X-3 |
1994 |
5 pages |
| Authors:
S. M. Matz; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; NORTHWESTERN UNIV EVANSTON IL DEPT OF PHYSICS AND ASTRONOMY
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| The OSSE instrument on the Compton Gamma-Ray Observatory (GRO) made 4 observations of Cygnus X-3 between May 1991 and December 1992. OSSE observed a substantial change in the average hard X-ray flux, which has previously been observed to be stable (variations < 20%). Over a 2-3 day period the flux above ~50 keV decreased by roughly a factor of 3. This occurred about 15 days prior to a large radio ... |
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| OSSE Observations of the Crab Pulsar |
1994 |
47 pages |
| Authors:
M. P. Ulmer; S. Lomatch; S. M. Matz; D. A. Grabelsky; W. R. Purcell; J. E. Grove; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; R. A. Cameron; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| We present results of the Compton Gamma Ray Observatory OSSE observations of the Crab pulsar, made during MJD 48373-48406 (27 April 1991-30 May 1991) and MJD 48798-48804 (25 June 1992-1 July 1992). Pulsar light curves and spectra over the ~0.05 to 10 MeV range are presented. The arrival time of the gamma-ray peak and the radio peak agree to within 30 microsecs, which is better than the ~300 microsecs accuracy ... |
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| OSSE Observations of the Galactic Center Region - Emission from Discrete Sources |
1994 |
6 pages |
| Authors:
G. V. Jung; J. D. Kurfess; W. N. Johnson; M. S. Strickman; R. L. Kinzer; W. R. Purcell; D. A. Grabelsky; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC
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| We present preliminary results on the X-ray emission of discrete sources in the Galactic Center region from OSSE observations made between July, 1991 and September, 1992. These observations were designed to investigate the distribution of galactic emission from the central region of our galaxy. The approach consists of scans through the Galactic Center with different position angles of the OSSE collimators' rectangular (3.8 deg. x 11.4 deg) field-of-view. The sources ... |
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| OSSE Observations of Blazars |
1994 |
6 pages |
| Authors:
K. McNaron-Brown; J. E. Grove; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; D. A. Grabelsky; W. R. Purcell; G. V. Jung; R. A. Cameron; GEORGE MASON UNIV FAIRFAX VA
|
| The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory has observed four of the active galactic nuclei detected by EGRET (Fichtel et at. 1993) at photon energies above 100 MeV; namely, 3C 273, 3C 279, MRK 421 and PKS 0528+134. These sources show blazar properties at other wavelengths. Only 3C 273 and 3C 279 were detected with high significance in the OSSE energy range, 0.05 - 10 ... |
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| The Distribution of Galactic 511 keV Positron Annihilation Radiation |
1994 |
11 pages |
| Authors:
W. R. Purcell; D. A. Grabelsky; M. P. Ulmer; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
|
| The Oriented Scintillation Spectrometer Experiment (OSSE) on NASA's Compton Gamma-Ray Observatory has completed numerous observations of the Galactic plane and Galactic center region. A principle objective of these observations was to measure the distribution of the Galactic positron annihilation radiation. Most of these observations provided positive detections of the narrow 511 keV annihilation line. These data were fitted using several diffuse distribution models representing various populations of progenitor objects. The ... |
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| Hard X Rays from Supernova 1993J |
1994 |
12 pages |
| Authors:
M. D. Leising; J. D. Kurfess; D. D. Clayton; D. A. Grabelsky; J. E. Grove; W. N. Johnson; G. V. Jung; R. L. Kinzer; R. A. Kroeger; W. R. Purcell; M. S. Strickman; L.-S The; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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| The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Observatory observed SN 1993J during three intervals centered approximately 12, 30, and 108 days after its outburst. Hard X-ray emission was detected in the first two of these intervals. No emission was seen in the third observation or in two earlier observations in 1991 and 1992. The coincidence of the observed excess with the outburst of SN 1993J and the consistency ... |
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| The Canonical Seyfert Spectrum: The Implications of OSSE Observations |
1994 |
11 pages |
| Authors:
W. N. Johnson; J. E. Grove; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; M. S. Strickman; K. McNaron-Brown; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
|
| In its first two years of operation, the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) observed 26 active galaxies classified as Seyferts. These objects were selected for their historical X-ray characteristics as identified by HEAO-1, EXOSAT and Ginga and include three of the gamma-ray emitting AGN detected prior to the launch of CGRO. OSSE detects approximately half of these objects at a significance of 5 ... |
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| The Pulsed Hard X-Ray Spectrum of PSR B1509-58 |
1994 |
11 pages |
| Authors:
S. M. Matz; M. P. Ulmer; D. A. Grabelsky; W. R. Purcell; J. E. Grove; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
|
| OSSE observed the 150 ms X-ray pulsar PSR B1509-58 in the supernova remnant MSH 15-52 for four weeks in 1992. The pulsed spectrum from 50 keV to 5 MeV is well-fit by a single power law photon spectrum of the form (3.14 plus or minus 0.16) x 10(exp 6) x(E/118.5 keV)(exp-1.68 plus or minus 0.09) photons cm(exp-2) s(exp-1) keV(exp -1). this is significantly harder than the Crab pulsar spectrum in ... |
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| Gamma-Ray and Radio Observations of PSR B1509-58 |
06 MAY 1993 |
17 pages |
| Authors:
M. P. Ulmer; S. M. Matz; R. B. Wilson; M. J. Finger; K. S. Hagedon; D. A. Grabelsky; J. E. Grove; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; W. R. Purcell; M. S. Strickman; V. M. Kaspi; S. Johnston; R. N. Manchester; A. G. Lyne; N. D'Amico; NORTHWESTERN UNIV EVANSTON IL DEPT OF PHYSICS AND ASTRONOMY
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| We report concurrent radio and gamma-ray observations of PSR B1509-58 carried out by the Parkes Radio Telescope and by the Burst and Transient Source Experiment (BATSE) and the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO-Gamma-ray light curves fitted at several energies between ~ 20-500 keV yield a phase offset with respect to the radio pulse that is independent of energy, with an average value 0.32 ... |
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| OSSE Observations of Galactic Sources During Phase I |
1993 |
12 pages |
| Authors:
J. D. Kurfess; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; M. S. Strickman; J. E. Grove; D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC
|
| The Oriented Scintillation Spectrometer Experiment (OSSE) on the COMPTON Gamma Ray Observatory has undertaken comprehensive observations of astrophysical sources during the eighteen-month Phase 1 of the mission. These include investigations of many galactic sources, including binary X-ray sources, pulsars, several transient X-ray sources observed as Targets-of-Opportunity, and Nova Cygni 1992. Multiple observations of the galactic center region were undertaken to map the diffuse galactic emission and search for point sources. ... |
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| Observation of the Starburst Galaxy NGC 253 with the OSSE Instrument |
1993 |
7 pages |
| Authors:
Dipen Bhattacharya; Neil Gehrels; J. D. Kurfess; W. N. Johnson; R. L. Kinzer; M. S. Strickman; Lih-Sin The; G. V. Jung; D. A. Grabelsky; W. R. Purcell; NAVAL RESEARCH LAB WASHINGTON DC
|
| Gamma-ray observations of the nearby starburst galaxy NGC 253 over the energy range 0.06 -10 MeV have been obtained with the OSSE spectrometer. The source was detected up to 200 keV with a total significance of 4.2sigma. When attributed to NGC 253 this corresponds to an estimated luminosity of 3 x 10(exp 40) ergs s(exp-1). The spectrum is fit by a power law of photon index ~ 2.5. A search ... |
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| OSSE Spectral Observations of GX 339-4 and CYG X-1 |
1993 |
6 pages |
| Authors:
D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; M. S. Strickman; J. E. Grove; R. A. Cameron; G. V. Jung; M. D. Leising; NAVAL RESEARCH LAB WASHINGTON DC
|
| The Oriented Scintillation Spectrometer Experiment on the Compton Gamma Ray Observatory has carried out spectral and timing observations of Galactic black-hole candidates GX 339-4 and Cyg X-1. GX 339-4 was observed as a target of opportunity in 1991 September, in response to the outburst reported by BATSE and SIGMA. The source was detected from 50 to 400 keV, at a level relative to the Crab of 30%. During a follow- ... |
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| OSSE Observations of the Vela Pulsar |
1993 |
5 pages |
| Authors:
M. S. Strickman; J. E. Grove; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; D. A. Grabelsky; S. M. Matz; W. R. Purcell; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC
|
| The OSSE detector on board the Compton Gamma Ray Observatory observed the Vela Pulsar (PSR 0833-45) during August-September 1991 and April-May 1992. Pulsed emission was detected at the 4-5 sigma level in the 0.06-0.57 MeV band in the sum of the two observing periods, as well as in each individual observation at lower significance. There is no significant variability observed. Light curves have a peak structure similar to that observed ... |
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| OSSE Observations of 57Co In SN1987A |
1992 |
9 pages |
| Authors:
J. D. Kurfess; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; M. S. Strickman; J. E. Grove; M. D. Leising; D. D. Clayton; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; R. A. Cameron; G. V. Jung; NAVAL RESEARCH LAB WASHINGTON DC
|
| The Oriented Scintillation Spectrometer Experiment (OSSE) on the COMPTON Gamma Ray Observatory has observed SN1987A for two 2-week periods during the first nine months of the mission. Evidence for gamma-ray line and continuum emission from 57Co is observed with an intensity of about 10(exp-4) gamma-/sq cm s(exp -1). This photon flux between 50 and 136 keV is demonstrated by Monte Carlo calculations to be independent of the radial distribution of ... |
|
| OSSE Observations of NGC 4151 |
1992 |
18 pages |
| Authors:
M. Maisack; W. N. Johnson; R. L. Kinzer; M. S. Strickman; J. D. Kurfess; R. A. Cameron; G. V. Jung; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; GEORGE MASON UNIV FAIRFAX VA
|
| We report results of a two-week observation of the Seyfert galaxy NGC 4151 with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory (GRO). The source had a very soft spectrum which is best represented by a broken power law or Sunyaev-Titarchuk thermal Comptonization model. It can be characterized by an exponential shape with an e-folding energy of 39 plus or minus 2 keV in the ... |
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| OSSE Observations of Cosmic Gamma-Ray Bursts |
1992 |
7 pages |
| Authors:
G. H. Share; W. N. Johnson; R. L. Kinzer; R. A. Kroeger; J. D. Kurfess; R. J. Murphy; M. S. Strickman; S. M. Matz; D. A. Grabelsky; W. R. Purcell; M. P. Ulmer; R. A. Cameron; G. V. Jung; J. E. Grove; NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
|
| The Oriented Scintillation Spectrometer Experiment detected over 80 cosmic gamma-ray bursts from mid-April to late November 1991. Data at 16 ms resolution were accumulated from its large-area NaI shields in response to BATSE triggers. Rates in excess of 5000 cts/16 ms were observed from the 1991 May 3 burst. Bursts on June 1 and August 7 were observed in the spectrometer's aperture. Preliminary information on both the spectrum and location ... |
|
| OSSE Spectral Analysis Techniques |
1991 |
14 pages |
| Authors:
W. R. Purcell; K. M. Browny; D. A. Grabelsky; W. N. Johnsonz; G. V. Jungx; R. L. Kinzerz; R. A. Kroegerz; J. D. Kurfessz; S. M. Matz; M. S. Strickmanz; M. P. Ulmer; NAVAL RESEARCH LAB WASHINGTON DC
|
| Analysis of spectra from the Oriented Scintillation Spectrometer Experiment (OSSE) is complicated because of the typically low signal-to-noise (0.1%) and the large background variability. The OSSE instrument was designed to address these di culties by periodically o set-pointing the detectors from the source to perform background measurements. These background measurements are used to estimate the background during each of the source observations. The resulting background- subtracted spectra can then be ... |
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| OSSE Observations of Galactic 511 KeV Annihilation Radiation |
1991 |
9 pages |
| Authors:
W. R. Purcell; D. A. Grabelsky; W. N. Johnson; G. V. Jung; R. L. Kinzer; J. D> Kurfess; M. S. Strickman; M. P. Ulmer; NORTHWESTERN UNIV EVANSTON IL
|
| The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory has performed several observations of the Galactic plane and Galactic center region to measure the distribution of Galactic 511 keV positron annihilation radiation. Preliminary analysis of data collected during the observation of the Galactic center region over the period July 13{24, 1991, indicates the presence of a 511 keV line and positronium continuum superimposed on a power-law continuum. |
|
| OSSE Observations of the Crab Pulsar |
1991 |
10 pages |
| Authors:
M. P. Ulmer; S. M. Matz; R. A. Cameron; D. A. Grabelsky; J. E. Grove; W. N. Johnson; G. V. Jung; R. L. Kinzer; J. D. Kurfess; M. D. Leising; W. R. Purcell; M. S. Strickman; NORTHWESTERN UNIV EVANSTON IL
|
| We present preliminary results of the Compton Gamma Ray Observatory OSSE observations of the Crab pulsar. The pulsar energy spectra and light curves are in general agreement with previous observations, validating the OSSE pulsar data acquisition modes and data analysis algorithms. The data suggest that the spectrum of the pulsar varies throughout the light curve. The "interpulse" region has a slightly flatter spectrum in the ~ 60-250 keV region and ... |
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