This dissertation presents the results from a balloon-borne experiment, referred to as the Directional Gamma-Ray Telescope (DGT), which is designed to image celestial gamma-rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique known as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of $3.8\\sp\\circ.$ This detector is the first flight-ready instrument of this type operating at energies above 160 keV. The first successful balloon flight of this instrument took place on 1984 October 1-2. During the thirty hours in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions.
The Crab Nebula/pulsar was observed to have a featureless power-law spectrum with a best fit form of $5.1 \\times 10\\sp{-3} {\\rm E\\sb{MeV}}\\sp{-1.88}$ photons ${\\rm cm\\sp{-2}\\ s\\sp{-1}\\ MeV}\\sp{-1},$ consistent with previous measurements. We have placed $3\\sigma$ upper limits on previously observed line emission at energies of 400 keV and 1049 keV; the results are $3.0 \\times 10\\sp{-3}$ and $1.9 \\times 10\\sp{-3}$ photons ${\\rm cm\\sp{-2}\\ s}\\sp{-1},$ respectively. These upper limits lie below some previous measurements of this emission. We also place upper limits on the emission from the x-ray binary source A0535+26 and the anticenter diffuse emission.
Emission from Cyg X-1 was observed up to $\\sim$10 MeV. At energies below 1 MeV, the data are consistent with a single-temperature inverse Compton model, with an electron temperature, ${\\rm kT\\sb{e}},$ of $\\sim$80 keV and an optical depth, $\\tau,$ of $\\sim$2.0. The inverse Compton model is often employed to explain the observed x-ray emission. In the 2-9.3 MeV range, the DGT results show emission which is not readily understood in the context of the inverse Compton model. We suggest that a second component, possibly produced by some non-thermal mechanism, may be necessary to explain the observations. Finally, upper limits are also derived for the flux from Cygnus X-3.
","abstract_html":"<p>This dissertation presents the results from a balloon-borne experiment, referred to as the Directional Gamma-Ray Telescope (DGT), which is designed to image celestial gamma-rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique known as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of $3.8\\sp\\circ.$ This detector is the first flight-ready instrument of this type operating at energies above 160 keV. The first successful balloon flight of this instrument took place on 1984 October 1-2. During the thirty hours in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions.</p><p>The Crab Nebula/pulsar was observed to have a featureless power-law spectrum with a best fit form of $5.1 \\times 10\\sp{-3} {\\rm E\\sb{MeV}}\\sp{-1.88}$ photons {\\rm cm\\sp{-2} s\\sp{-1} MeV}\\sp{-1}, consistent with previous measurements. We have placed 3σ upper limits on previously observed line emission at energies of 400 keV and 1049 keV; the results are $3.0 \\times 10\\sp{-3}$ and $1.9 \\times 10\\sp{-3}$ photons {\\rm cm\\sp{-2} s}\\sp{-1}, respectively. These upper limits lie below some previous measurements of this emission. We also place upper limits on the emission from the x-ray binary source A0535+26 and the anticenter diffuse emission.</p><p>Emission from Cyg X-1 was observed up to $\\sim$10 MeV. At energies below 1 MeV, the data are consistent with a single-temperature inverse Compton model, with an electron temperature, ${\\rm kT\\sb{e}},$ of $\\sim$80 keV and an optical depth, $\\tau,$ of $\\sim$2.0. The inverse Compton model is often employed to explain the observed x-ray emission. In the 2-9.3 MeV range, the DGT results show emission which is not readily understood in the context of the inverse Compton model. We suggest that a second component, possibly produced by some non-thermal mechanism, may be necessary to explain the observations. Finally, upper limits are also derived for the flux from Cygnus X-3.</p>","abstract_has_math":true,"creators":["MCCONNELL, MARK LEWIS"],"institution":null,"degree_name":"Doctor of Philosophy","degree_level":"Dissertation","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1987,"date_issued":"1987-01-01T08:00:00Z","date_published":"1987-01-01T08:00:00Z","updated_at":"2026-07-24T05:23:21Z","subjects":["Physics","Astronomy and Astrophysics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholars.unh.edu/dissertation/1512","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["MCCONNELL, MARK LEWIS"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics","Astronomy and Astrophysics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholars.unh.edu/dissertation/1512"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This dissertation presents the results from a balloon-borne experiment, referred to as the Directional Gamma-Ray Telescope (DGT), which is designed to image celestial gamma-rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique known as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of $3.8\\sp\\circ.$ This detector is the first flight-ready instrument of this type operating at energies above 160 keV. The first successful balloon flight of this instrument took place on 1984 October 1-2. During the thirty hours in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions.
The Crab Nebula/pulsar was observed to have a featureless power-law spectrum with a best fit form of $5.1 \\times 10\\sp{-3} {\\rm E\\sb{MeV}}\\sp{-1.88}$ photons ${\\rm cm\\sp{-2}\\ s\\sp{-1}\\ MeV}\\sp{-1},$ consistent with previous measurements. We have placed $3\\sigma$ upper limits on previously observed line emission at energies of 400 keV and 1049 keV; the results are $3.0 \\times 10\\sp{-3}$ and $1.9 \\times 10\\sp{-3}$ photons ${\\rm cm\\sp{-2}\\ s}\\sp{-1},$ respectively. These upper limits lie below some previous measurements of this emission. We also place upper limits on the emission from the x-ray binary source A0535+26 and the anticenter diffuse emission.
Emission from Cyg X-1 was observed up to $\\sim$10 MeV. At energies below 1 MeV, the data are consistent with a single-temperature inverse Compton model, with an electron temperature, ${\\rm kT\\sb{e}},$ of $\\sim$80 keV and an optical depth, $\\tau,$ of $\\sim$2.0. The inverse Compton model is often employed to explain the observed x-ray emission. In the 2-9.3 MeV range, the DGT results show emission which is not readily understood in the context of the inverse Compton model. We suggest that a second component, possibly produced by some non-thermal mechanism, may be necessary to explain the observations. Finally, upper limits are also derived for the flux from Cygnus X-3.
"]},{"key":"dc:title","label":"Title","values":["GAMMA-RAY IMAGING OBSERVATIONS OF THE CRAB AND CYGNUS REGIONS"]}]}],"canonical_facts":{"dc:creator":["MCCONNELL, MARK LEWIS"],"dc:description.abstract":["This dissertation presents the results from a balloon-borne experiment, referred to as the Directional Gamma-Ray Telescope (DGT), which is designed to image celestial gamma-rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique known as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of $3.8\\sp\\circ.$ This detector is the first flight-ready instrument of this type operating at energies above 160 keV. The first successful balloon flight of this instrument took place on 1984 October 1-2. During the thirty hours in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions.
The Crab Nebula/pulsar was observed to have a featureless power-law spectrum with a best fit form of $5.1 \\times 10\\sp{-3} {\\rm E\\sb{MeV}}\\sp{-1.88}$ photons ${\\rm cm\\sp{-2}\\ s\\sp{-1}\\ MeV}\\sp{-1},$ consistent with previous measurements. We have placed $3\\sigma$ upper limits on previously observed line emission at energies of 400 keV and 1049 keV; the results are $3.0 \\times 10\\sp{-3}$ and $1.9 \\times 10\\sp{-3}$ photons ${\\rm cm\\sp{-2}\\ s}\\sp{-1},$ respectively. These upper limits lie below some previous measurements of this emission. We also place upper limits on the emission from the x-ray binary source A0535+26 and the anticenter diffuse emission.
Emission from Cyg X-1 was observed up to $\\sim$10 MeV. At energies below 1 MeV, the data are consistent with a single-temperature inverse Compton model, with an electron temperature, ${\\rm kT\\sb{e}},$ of $\\sim$80 keV and an optical depth, $\\tau,$ of $\\sim$2.0. The inverse Compton model is often employed to explain the observed x-ray emission. In the 2-9.3 MeV range, the DGT results show emission which is not readily understood in the context of the inverse Compton model. We suggest that a second component, possibly produced by some non-thermal mechanism, may be necessary to explain the observations. Finally, upper limits are also derived for the flux from Cygnus X-3.
"],"dc:identifier":["https://scholars.unh.edu/dissertation/1512"],"dc:subject":["Physics","Astronomy and Astrophysics"],"dc:title":["GAMMA-RAY IMAGING OBSERVATIONS OF THE CRAB AND CYGNUS REGIONS"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy"]},"updated_at":"2026-07-24T05:23:21Z"}