FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Au... more FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operation of a robotic telescope for such a purpose and their implementation within the FRAM system.
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby as... more The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.
The optical calibration of the fluorescence telescopes is a significant contribution to the overa... more The optical calibration of the fluorescence telescopes is a significant contribution to the overall uncertainty of energy measurements made by the Pierre Auger Observatory and Telescope Array Project. Some sources of uncertainty, such as the fluorescence yield in air, affect both experiments similarly. However, the optical calibration of the fluorescence telescopes is a source of independent uncertainty. The Pierre Auger and Telescope Array collaborations have taken initial steps to establish a relative end-to-end optical calibration of the fluorescence telescopes. An Octocopter carrying a portable light source has been flown in front of fluorescence telescopes at both Pierre Auger and Telescope Array sites. Laboratory calibration measurements of the light source before and after the flights provide a common baseline for the relative end-to-end calibration. We expect this system will lead to a common photonic calibration for both experiments. After giving a brief description of the ...
Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, i... more Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, including examination of hadronic physics effects on the structure of extensive air showers.
Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, ... more Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Au... more FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operation of a robotic telescope for such a purpose and their implementation within the FRAM system.
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby as... more The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.
The optical calibration of the fluorescence telescopes is a significant contribution to the overa... more The optical calibration of the fluorescence telescopes is a significant contribution to the overall uncertainty of energy measurements made by the Pierre Auger Observatory and Telescope Array Project. Some sources of uncertainty, such as the fluorescence yield in air, affect both experiments similarly. However, the optical calibration of the fluorescence telescopes is a source of independent uncertainty. The Pierre Auger and Telescope Array collaborations have taken initial steps to establish a relative end-to-end optical calibration of the fluorescence telescopes. An Octocopter carrying a portable light source has been flown in front of fluorescence telescopes at both Pierre Auger and Telescope Array sites. Laboratory calibration measurements of the light source before and after the flights provide a common baseline for the relative end-to-end calibration. We expect this system will lead to a common photonic calibration for both experiments. After giving a brief description of the ...
Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, i... more Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, including examination of hadronic physics effects on the structure of extensive air showers.
Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, ... more Contributions of the Pierre Auger Collaboration to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013
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Papers by Rodrigo Pelayo