The occurrence times of energetic (above 10 MeV) solar flare electron events observed on board th... more The occurrence times of energetic (above 10 MeV) solar flare electron events observed on board the ISEE 3 spacecraft during the years 1978-1982 have been examined; strong evidence is found for a periodicity of 153 + or - 2 days, confirming the discovery of a periodicity in the occurrence of solar flares producing X-rays and gamma rays. The Rayleigh test
Her X-l has been observed for 73 hours with the Whipple Observatory Cerenkov imaging camera on th... more Her X-l has been observed for 73 hours with the Whipple Observatory Cerenkov imaging camera on the 10m reflector between April 1984 and June 1985. Seven distinct episodes of emission were seen, ranging in duration from 25 to 80 minutes, totalling 7% of all observations. Evidence is presented which suggests that the gamma-ray source is not always coincident with the X-ray source; in particular, the strongest effect was observed after the pulsar entered eclipse. All effects were observed to occur during the active states of the 35 day X-ray cycle.
VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and ... more VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and will start operating by January 2007. We give a brief report of the construction status and performance characteristics of the telescopes.
A method of event selection based on pattern recognition is used to analyse high energy gamma ray... more A method of event selection based on pattern recognition is used to analyse high energy gamma ray observations of pulsars with periods 6 and 33 msec.
ABSTRACT The transient X-ray binary pulsar 4U0115+63 has been observed for 37 h by the Whipple Ob... more ABSTRACT The transient X-ray binary pulsar 4U0115+63 has been observed for 37 h by the Whipple Observatory Cerenkov imaging camera between September 1985 and January 1986. These observations were grouped into nine intervals of 3 d or less. One interval shows significant pulsation at the 3.6-sec spin period of the neutron star member of the binary system at a flux level of (1.5 + or - 0.4) x 10 to the -10th photons/sq cm sec above 600 GeV. Thus these observations confirm previous detections, with an indication that the TeV emission may be sporadic.
ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in the... more ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in their evaluation of options to reduce the negative impacts of climate change. Certain attributes of an assessment can improve the use or uptake of its results. The science policy literature describes three characteristics – credibility, salience, and legitimacy – as being necessary for the uptake of scientific results for decision-making. We draw from the experiences of eight climate change vulnerability assessments conducted in Africa and Latin America for USAID (United States Agency for International Development) to explore the practical application of these three characteristics to fostering uptake of the assessment results.
ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in the... more ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in their evaluation of options to reduce the negative impacts of climate change. Certain attributes of an assessment can improve the use or uptake of its results. The science policy literature describes three characteristics – credibility, salience, and legitimacy – as being necessary for the uptake of scientific results for decision-making. We draw from the experiences of eight climate change vulnerability assessments conducted in Africa and Latin America for USAID (United States Agency for International Development) to explore the practical application of these three characteristics to fostering uptake of the assessment results.
VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is one of a new generation ... more VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is one of a new generation of ground-based gamma-ray observatories. It is being built by a collaboration of ten institutions from Canada, Ireland, the U.K. and the U.S.A. VERITAS uses the imaging atmospheric Cherenkov technique (IACT) which was developed by the Whipple collaboration using the Whipple 10m telescope. The 10m was the first ground-based gamma-ray telescope to detect both galactic and extragalactic sources of TeV gamma rays. VERITAS is designed to operate in the range from 50 GeV to 50 TeV with optimal sensitivity near 200 GeV; it will effectively overlap with the next generation of space-based gamma-ray telescopes.
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently ... more The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral hydrogen in the frequency range 400-800 MHz over half of the sky, producing a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8-2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that
A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently b... more A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently being commissioned at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical interferometer designed to measure the large scale neutral hydrogen power spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used to measure the baryon acoustic oscillation (BAO) scale across this poorly probed redshift range where dark energy becomes a significant contributor to the evolution of the Universe. The instrument revives the cylinder design in radio astronomy with a wide field survey as a primary goal. Modern low-noise amplifiers and digital processing remove the necessity for the analog beamforming that characterized previous designs. The Pathfinder consists of two cylinders 37 m long by 20 m wide oriented northsouth for a total collecting area of 1,500 square meters. The cylinders are stationary with no moving parts, and form a transit instrument with an instantaneous field of view of ∼100 degrees by 1-2 degrees. Each CHIME
We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident wi... more We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hours during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (σ) before trials and 7.5 σ after trials in a point-source search. The emission is centered at 6 h 16 m 51 s + 22°30 ′ 11 ′′ (J2000) ±0.03°s tat ± 0.08°s ys , with an intrinsic extension of 0.16°± 0.03°s tat ± 0.04°s ys. The VHE spectrum is well fit by a power law (dN/dE = N 0 × (E/TeV) −Γ) with a photon index of 2.99 ± 0.38 stat ± 0.3 sys and an integral flux above 300 GeV of (4.63 ± 0.90 stat ± 0.93 sys) × 10 −12 cm −2 s −1. These results are discussed in the context of existing models for gamma-ray production in IC 443.
ABSTRACT Observations of Geminga made at the Whipple Observatory using the atmospheric Cherenkov ... more ABSTRACT Observations of Geminga made at the Whipple Observatory using the atmospheric Cherenkov technique during the moonless periods of November 1983 to February 1984 and November 1984 till February 1985 were examined for evidence for the emission of gamma rays with energy in excess of approx 400 GeV. Evidence of either a steady flux or a flux pulsed with a period near 60 seconds were studied. In neither case was any significant effect observed, enabling the establishment 3 of sigma upper limits of 5.5 x 10 to the -11th power photons/sq cm/s and 2.0 x 10 to the -11th power photons/sq cm/s for the steady and pulsed emission respectively. The limit to the pulsed flux is approximately a factor of six below that predicted.
We present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident wi... more We present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hr during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (σ) before trials and 7.5σ after trials in a point-source search. The emission is centered at 6 h 16 m 51 s +22 • 30 11 (J2000) ±0. • 03 stat ±0. • 08 sys , with an intrinsic extension of 0. • 16 ± 0. • 03 stat ± 0. • 04 sys. The VHE spectrum is well fit by a power law (dN/dE = N 0 × (E/TeV) −Γ) with a photon index of 2.99 ± 0.38 stat ± 0.3 sys and an integral flux above 300 GeV of (4.63 ± 0.90 stat ± 0.93 sys) × 10 −12 cm −2 s −1. These results are discussed in the context of existing models for gamma-ray production in IC 443.
The occurrence times of energetic (above 10 MeV) solar flare electron events observed on board th... more The occurrence times of energetic (above 10 MeV) solar flare electron events observed on board the ISEE 3 spacecraft during the years 1978-1982 have been examined; strong evidence is found for a periodicity of 153 + or - 2 days, confirming the discovery of a periodicity in the occurrence of solar flares producing X-rays and gamma rays. The Rayleigh test
Her X-l has been observed for 73 hours with the Whipple Observatory Cerenkov imaging camera on th... more Her X-l has been observed for 73 hours with the Whipple Observatory Cerenkov imaging camera on the 10m reflector between April 1984 and June 1985. Seven distinct episodes of emission were seen, ranging in duration from 25 to 80 minutes, totalling 7% of all observations. Evidence is presented which suggests that the gamma-ray source is not always coincident with the X-ray source; in particular, the strongest effect was observed after the pulsar entered eclipse. All effects were observed to occur during the active states of the 35 day X-ray cycle.
VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and ... more VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and will start operating by January 2007. We give a brief report of the construction status and performance characteristics of the telescopes.
A method of event selection based on pattern recognition is used to analyse high energy gamma ray... more A method of event selection based on pattern recognition is used to analyse high energy gamma ray observations of pulsars with periods 6 and 33 msec.
ABSTRACT The transient X-ray binary pulsar 4U0115+63 has been observed for 37 h by the Whipple Ob... more ABSTRACT The transient X-ray binary pulsar 4U0115+63 has been observed for 37 h by the Whipple Observatory Cerenkov imaging camera between September 1985 and January 1986. These observations were grouped into nine intervals of 3 d or less. One interval shows significant pulsation at the 3.6-sec spin period of the neutron star member of the binary system at a flux level of (1.5 + or - 0.4) x 10 to the -10th photons/sq cm sec above 600 GeV. Thus these observations confirm previous detections, with an indication that the TeV emission may be sporadic.
ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in the... more ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in their evaluation of options to reduce the negative impacts of climate change. Certain attributes of an assessment can improve the use or uptake of its results. The science policy literature describes three characteristics – credibility, salience, and legitimacy – as being necessary for the uptake of scientific results for decision-making. We draw from the experiences of eight climate change vulnerability assessments conducted in Africa and Latin America for USAID (United States Agency for International Development) to explore the practical application of these three characteristics to fostering uptake of the assessment results.
ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in the... more ABSTRACT Findings from climate change vulnerability assessments can inform decision-makers in their evaluation of options to reduce the negative impacts of climate change. Certain attributes of an assessment can improve the use or uptake of its results. The science policy literature describes three characteristics – credibility, salience, and legitimacy – as being necessary for the uptake of scientific results for decision-making. We draw from the experiences of eight climate change vulnerability assessments conducted in Africa and Latin America for USAID (United States Agency for International Development) to explore the practical application of these three characteristics to fostering uptake of the assessment results.
VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is one of a new generation ... more VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is one of a new generation of ground-based gamma-ray observatories. It is being built by a collaboration of ten institutions from Canada, Ireland, the U.K. and the U.S.A. VERITAS uses the imaging atmospheric Cherenkov technique (IACT) which was developed by the Whipple collaboration using the Whipple 10m telescope. The 10m was the first ground-based gamma-ray telescope to detect both galactic and extragalactic sources of TeV gamma rays. VERITAS is designed to operate in the range from 50 GeV to 50 TeV with optimal sensitivity near 200 GeV; it will effectively overlap with the next generation of space-based gamma-ray telescopes.
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently ... more The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral hydrogen in the frequency range 400-800 MHz over half of the sky, producing a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8-2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that
A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently b... more A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently being commissioned at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical interferometer designed to measure the large scale neutral hydrogen power spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used to measure the baryon acoustic oscillation (BAO) scale across this poorly probed redshift range where dark energy becomes a significant contributor to the evolution of the Universe. The instrument revives the cylinder design in radio astronomy with a wide field survey as a primary goal. Modern low-noise amplifiers and digital processing remove the necessity for the analog beamforming that characterized previous designs. The Pathfinder consists of two cylinders 37 m long by 20 m wide oriented northsouth for a total collecting area of 1,500 square meters. The cylinders are stationary with no moving parts, and form a transit instrument with an instantaneous field of view of ∼100 degrees by 1-2 degrees. Each CHIME
We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident wi... more We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hours during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (σ) before trials and 7.5 σ after trials in a point-source search. The emission is centered at 6 h 16 m 51 s + 22°30 ′ 11 ′′ (J2000) ±0.03°s tat ± 0.08°s ys , with an intrinsic extension of 0.16°± 0.03°s tat ± 0.04°s ys. The VHE spectrum is well fit by a power law (dN/dE = N 0 × (E/TeV) −Γ) with a photon index of 2.99 ± 0.38 stat ± 0.3 sys and an integral flux above 300 GeV of (4.63 ± 0.90 stat ± 0.93 sys) × 10 −12 cm −2 s −1. These results are discussed in the context of existing models for gamma-ray production in IC 443.
ABSTRACT Observations of Geminga made at the Whipple Observatory using the atmospheric Cherenkov ... more ABSTRACT Observations of Geminga made at the Whipple Observatory using the atmospheric Cherenkov technique during the moonless periods of November 1983 to February 1984 and November 1984 till February 1985 were examined for evidence for the emission of gamma rays with energy in excess of approx 400 GeV. Evidence of either a steady flux or a flux pulsed with a period near 60 seconds were studied. In neither case was any significant effect observed, enabling the establishment 3 of sigma upper limits of 5.5 x 10 to the -11th power photons/sq cm/s and 2.0 x 10 to the -11th power photons/sq cm/s for the steady and pulsed emission respectively. The limit to the pulsed flux is approximately a factor of six below that predicted.
We present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident wi... more We present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hr during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (σ) before trials and 7.5σ after trials in a point-source search. The emission is centered at 6 h 16 m 51 s +22 • 30 11 (J2000) ±0. • 03 stat ±0. • 08 sys , with an intrinsic extension of 0. • 16 ± 0. • 03 stat ± 0. • 04 sys. The VHE spectrum is well fit by a power law (dN/dE = N 0 × (E/TeV) −Γ) with a photon index of 2.99 ± 0.38 stat ± 0.3 sys and an integral flux above 300 GeV of (4.63 ± 0.90 stat ± 0.93 sys) × 10 −12 cm −2 s −1. These results are discussed in the context of existing models for gamma-ray production in IC 443.
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Papers by Kenneth Gibbs