196,823 research outputs found
Impact of Laser Guide Star facilities on neighbouring telescopes: the case of GTC, TMT, VLT, and ELT lasers and the Cherenkov Telescope Array
No full textReflecting on Cherenkov reflections
No full textMagic Telescope may observe and reveal at horizons lights from air-shower Cherenkov reflections. The ground, the sea, the cloudy sky (below the mountain) may reflect PeVs-EeV UHECR Cherenkov lights observable by MAGIC telescopes. Even rarest UHE neutrino skimming the atmosphere or skimming the Earth may induce upward-horizontal airshowers: a new Neutrino Astronomy. These fluorescence signals or the Cherenkov reflections in upper cloudy sky may flash in correlated BL-Lac or GRB shining at opposite edges. Geomagnetic splitting of Horizontal Air-showers may offer a new spectroscopy of UHECR from the knee up to GZK energy edges
Preliminary optical design of a polychromator for a Raman LIDAR for atmospheric calibration of the Cherenkov Telescope Array
No full textThe preliminary design of a polychromator unit for a Raman lidar (Light Detection And Ranging) for atmospheric calibration in the framework of the Cherenkov Telescope Array (CTA) project is presented. To obtain high quality data from CTA, a precise monitoring of the atmospheric transmission is needed. Remote-sensing instruments, like elastic/Raman lidars, have already been proven a powerful tool in environmental studies, and a lidar installed and operated at the CTA site is foreseen for correcting systematic biases on the energy and flux. The lidar we discuss here consists of a powerful laser that emits light pulses into the atmosphere, a mirror of 1.8 m diameter that collects the backscattered light and a polychromator unit where the light is analyzed. The laser is a pulsed Nd:YAG with the first two harmonics available at 355 and 532 nm and the polychromator has 4 read-out channels: two to analyze the elastic backscattering at 355 and 532 nm and two for the Raman Nitrogen back-scattered light, at 387 and 607 nm, respectively. The polychromator module needs to collect the majority of the light coming from the telescope, to split the different wavelengths and to focus the beams onto photomultiplier detectors. The collection and focalization of the beams are done by means of simple lens-couples and the separation with custom-made dichroic mirrors and narrow-band filters. The performance of the conceived optical design, the adopted design choices for the glass, surface figure and size of the lenses, and the expected throughput for the different channels are hereafter described. © 2012 SPIE
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Strategy implementation for the CTA Atmospheric monitoring program
No full textThe Cherenkov Telescope Array (CTA) is the next generation facility of Imaging Atmospheric Cherenkov Telescopes. It reaches unprecedented sensitivity and energy resolution in very-high-energy gamma-ray astronomy. CTA detects Cherenkov light emitted within an atmospheric shower of particles initiated by cosmic-gamma rays or cosmic rays entering the Earth's atmosphere. From the combination of images the Cherenkov light produces in the telescopes, one is able to infer the primary particle energy and direction. A correct energy estimation can be thus performed only if the local atmosphere is well characterized. The atmosphere not only affects the shower development itself, but also the Cherenkov photon transmission from the emission point in the particle shower, at about 10-20 km above the ground, to the detector. Cherenkov light on the ground is peaked in the UV-blue region, and therefore molecular and aerosol extinction phenomena are important. The goal of CTA is to control systematics in energy reconstruction to better than 10%. For this reason, a careful and continuous monitoring and characterization of the atmosphere is required. In addition, CTA will be operated as an observatory, with data made public along with appropriate analysis tools. High-level data quality can only be ensured if the atmospheric properties are consistently and continuously taken into account. In this contribution, we concentrate on discussing the implementation strategy for the various atmospheric monitoring instruments currently under discussion in CTA. These includes Raman lidars and ceilometers, stellar photometers and others available both from commercial providers and public research centers
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Upper limits on GeV--TeV gamma-ray emission for follow-up observations with the MAGIC telescope
No full textDuring the first observation cycle of the MAGIC telescope, 9 successful GRB follow-up observations were performed. For 2 bursts, the obser- vation started even while the prompt emission was still ongoing. In none of these observations a significant excess over background could be detected. We present a direct determination of the MAGIC sensitivity in GRB observation mode from the Crab Nebula and the obtained upper limits for the 9 observations. At energies around 100 GeV, MAGIC is currently the fastest and most sensitive GRB detector in the world
Analysis techniques and performance of the Domino Ring Sampler version 4 based readout for the MAGIC telescopes
No full textRecently the readout of the MAGIC telescopes has been upgraded to a new system based on the Domino Ring Sampler version 4 chip. We present the analysis techniques and the signal extraction performance studies of this system. We study the behavior of the baseline, the noise, the cross-talk, the linearity and the time resolution. We investigate also the optimal signal extraction. In addition we show some of the analysis techniques specific to the readout based on the Domino Ring Sampler version 2 chip, previously used in the MAGIC II telescope. (C) 2013 Elsevier B.V. All rights reserved
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