Complejo Astronomico El Leoncito

San Juan, Argentina

Complejo Astronomico El Leoncito

San Juan, Argentina

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Makhmutov V.S.,RAS Lebedev Physical Institute | Stozhkov Y.I.,RAS Lebedev Physical Institute | Raulin J.-P.,Mackenzie Presbyterian University | Philippov M.V.,RAS Lebedev Physical Institute | And 7 more authors.
Bulletin of the Russian Academy of Sciences: Physics | Year: 2017

Three units of neutron detectors and four blocks of gamma-ray spectrometers have been installed and started operation at Complejo Astronomico El Leoncito, CASLEO (San Juan, Argentina; coordinates 31 S, 69 W; height of 2550 m; the rigidity of geomagnetic cutoff of Rc = 9.7 GV) in May 2015 as part of the scientific cooperation between the Lebedev Physical Institute, Russian Academy of Sciences (Moscow, Russia), Universidade Presbiteriana Mackenzie (San Paulo, Brazil) and Complejo Astronomico El Leoncito, CASLEO (San Juan, Argentina). Measurements with the new detectors greatly supplement the experimental data on variations in the charged component of cosmic rays obtained by the CARPET ground-based cosmic ray detector in 2006. The first results from a joint analysis of new experimental data are presented. Particular attention is given to growing cosmic ray fluxes associated with changes in the surface electric field. The main characteristics of the events recorded in January 2016 are presented. © 2017, Allerton Press, Inc.


De Mendonca R.R.S.,National Institute for Space Research | Echer E.,National Institute for Space Research | Makhmutov V.S.,RAS Lebedev Physical Institute | Fernandez G.,Complejo Astronomico El Leoncito
Journal of Geophysical Research: Space Physics | Year: 2013

In this paper, we analyze atmospheric pressure and temperature effects on the records of the cosmic ray detector CARPET. This detector has monitored secondary cosmic ray intensity since 2006 at Complejo Astronõmico El Leoncito (San Juan, Argentina, 31°S, 69°W, 2550 m over sea level) where the geomagnetic rigidity cutoff, Rc, is ~9.8 GV. From the correlation between atmospheric pressure deviations and relative cosmic ray variations, we obtain a barometric coefficient of -0.44 ± 0.01 %/hPa. Once the data are corrected for atmospheric pressure, they are used to analyze temperature effects using four methods. Three methods are based on the surface temperature and the temperature at the altitude of maximum production of secondary cosmic rays. The fourth method, the integral method, takes into account the temperature height profile between 14 and 111 km above Complejo Astronõmico El Leoncito. The results obtained from these four methods are compared on different time scales from seasonal time variations to scales related to the solar activity cycle. Our conclusion is that the integral method leads to better results to remove the temperature effect of the cosmic ray intensity observed at ground level. Key Points Analysis of pressure effect on cosmic rays flux observed at groundAnalysis of temperature effect on cosmic rays flux observed at groundGround cosmic ray detector data correction by pressure and temperature effects ©2012. American Geophysical Union. All Rights Reserved.


De Mendonca R.R.S.,National Institute for Space Research | Echer E.,National Institute for Space Research | Makhmutov V.S.,RAS Lebedev Physical Institute | Fernandez G.,Complejo Astronomico el Leoncito
Proceedings of the 32nd International Cosmic Ray Conference, ICRC 2011 | Year: 2011

The CARPET detector has monitored cosmic ray counts since 2006, at CASLEO observatory (S 31.8 W 69.3; Rc ∼ 12 GV). We present four different methods for atmospheric temperature correction of the recorded flux. While one of these is an integral method, the other three are empirical methods. We compare the resulting cosmic ray flux using these different corrections, in different timescales from seasonal time variations up to the timescale related to the solar activity cycle.


Martinis C.,Boston University | Wilson J.,University of New Hampshire | Zablowski P.,Boston University | Baumgardner J.,Boston University | And 5 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2013

A method for determining cloud cover fraction over El Leoncito Observatory (31.8°S, 69.3°W) is presented. Data from an all-sky imaging system, designed to measure nightglow originating from the mesosphere and thermosphere, is used to determine the fraction of the sky covered by clouds. More than 9,000 hr of observations from May 2006 to December 2010 are used to show that El Leoncito is clear approximately 75-80% of the time. No significant seasonal variations are observed. The optical ground-based data are compared with data from the Moderate Resolution Imaging Spectro-radiometer (MODIS) instrument on board the TERRA and AQUA satellites. © 2013. The Astronomical Society of the Pacific. All rights reserved.


Gausachs G.,Gemini Observatory | Bec M.,Gemini Observatory | Galvez R.,Gemini Observatory | Cavedoni C.,Gemini Observatory | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

CANOPUS is the facility instrument for the Gemini Multi Conjugate Adaptive Optics System (GeMS) wherein all the adaptive optics mechanisms and associated electronic are tightly packed. At an early stage in the pre-commissioning phase Gemini undertook the redesign and implementation of its chilled Ethylene Glycol Water (EGW) cooling system to remove the heat generated by the electronic hardware. The electronic boards associated with the Deformable Mirrors (DM) represent the highest density heat yielding components in CANOPUS and they are also quite sensitive to overheating. The limited size of the two electronic thermal enclosures (TE) requires the use of highly efficient heat exchangers (HX) coupled with powerful yet compact DC fans. A systematic approach to comply with all the various design requirements brought about a thorough and robust solution that, in addition to the core elements (HXs and fan), makes use of features such as high performance vacuum insulated panels, vibration mitigation elements and several environment sensors. This paper describes the design and implementation of the solution in the lab prior to delivering CANOPUS for commissioning. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Tacza J.,Mackenzie Presbyterian University | Raulin J.-P.,Mackenzie Presbyterian University | Macotela E.,Mackenzie Presbyterian University | Norabuena E.,Instituto Geofisico del Peru | And 5 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2014

In this paper we present the capability of a new network of field mill sensors to monitor the atmospheric electric field at various locations in South America; we also show some early results. The main objective of the new network is to obtain the characteristic Universal Time diurnal curve of the atmospheric electric field in fair weather, known as the Carnegie curve. The Carnegie curve is closely related to the current sources flowing in the Global Atmospheric Electric Circuit so that another goal is the study of this relationship on various time scales (transient/monthly/seasonal/annual). Also, by operating this new network, we may also study departures of the Carnegie curve from its long term average value related to various solar, geophysical and atmospheric phenomena such as the solar cycle, solar flares and energetic charged particles, galactic cosmic rays, seismic activity and specific meteorological events. We then expect to have a better understanding of the influence of these phenomena on the Global Atmospheric Electric Circuit and its time-varying behavior. © 2014.


Tacza J.C.,Mackenzie Presbyterian University | Raulin J.-P.,Mackenzie Presbyterian University | Macotela E.L.,Mackenzie Presbyterian University | Norabuena E.O.,Instituto Geofisico del Peru | Fernandez G.,Complejo Astronomico El Leoncito
Advances in Space Research | Year: 2016

In this paper, we study the variations of atmospheric electric field during the total solar eclipse (TSE) of July 11, 2010, at Complejo Astronómico El Leoncito (CASLEO). These variations observed with two identical sensors separated by 0.4. km, show a significant increase (∼55. V/m) when compared with averaged values measured during previous and subsequent fair weather days. Furthermore, identical changes are detected on the measured phases of Very Low Frequency waves received at CASLEO. The latter suggests a possible connection between the lower ionosphere and the lower atmosphere during the period of the eclipse. © 2016 COSPAR.


Cellino A.,National institute for astrophysics | Gil-Hutton R.,Complejo Astronomico El Leoncito
AAPP Atti della Accademia Peloritana dei Pericolanti, Classe di Scienze Fisiche, Matematiche e Naturali | Year: 2011

Asteroid polarimetry is known to be an excellent tool to derive information on the geometric albedo of these objects. This is made possible by the existence of a relation between the albedo and the morphology of the curve which describes the variation of the degree of linear polarization of asteroid light as a function of the illumination conditions. A major problem is that the calibration of the commonly accepted form of the polarization - albedo relation includes numerical coeffcients which are affected by fairly high uncertainties. Following some recommendations issued by IAU Commission 15, we are trying to improve the albedo - polarization relation by taking advantage of new po-larimetric data obtained in dedicated observation campaigns. We present here some very preliminary results. © 2011 by the Author(s); licensee Accademia Peloritana dei Pericolanti, Messina, Italy.

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