Aplicación del Sistema de Posicionamiento Global (GPS) al mapeo de barreras y barras intermareales, Rio Grande, Tierra del Fuego, Argentina

GPS mapping profiency of litoral features was analized during a planimetric survey in the Río Grande (Tierra del Fuego, Argentina) inlet. Two GPS Magellan Nav 5000 Pro were used applying differential processing. The expenence shows that: a) the method gives rapidly, and at a low cost, a litoral landforms measurement with a ( 5 m error; b) is weather independent and c) would allow for an inmediate mapping of significative morphological changes along the coast due to the occurrence of high energy waves

Anomalías de la refracción en Río Grande

Las variaciones estacionales no polares de Latitud, Tiempo y Distancia cenital en la EARS (Estación Astronómica Río Grande) sugieren un comportamiento anómalo de la refracción, asociable a la geografía local. En este informe se sugiere una explicación y se ensaya un modelo numérico empírico para la corrección de las observaciones. El interés de este trabajo no radica en lograr mejores resultados de Tiempo y Latitud, sino en desafectar a los residuos individuales de las estrellas, que se utilizan para las correcciones de catálogo, de un error debido a la refracción anómala.Asociación Argentina de Astronomí

Mantenimiento de tiempo preciso en la Estación Astronómica Río Grande

En el informe se exponen los resultados del trabajo de mantenimiento preciso del tiempo en la Estación Astronómica Río Grande (EARG) en Tierra del Fuego, desde el Observatorio Astronómico de La Plata (OALP), usando como referencia los patrones atómicos del Instituto Geográfico Militar, y del Observatorio Naval Buenos Aires. Se describe el equipamiento utilizado. Se usaron simultáneamente, cuatro métodos para el control del estado y marcha de relojes distantes, con determinaciones diarias o semanales, ellos son: - Señales de tiempo en onda corta (Emisiones del ONBA). - Comparación por señales comerciales de TV (Recepción directa, para distancias cortas y vía satélite, para largas). - Doble camino telefónico (DCT) (Equipo de diseño especial desarrollado en el OALP en 1990). - Transporte físico de reloj. Para cada uno de ellos se analizan: ventajas e inconvenientes y los resultados obtenidos. Se dedica especial atención al DCT dada su reciente instalación.Asociación Argentina de Astronomí

Aplicación del Sistema de Posicionamiento Global (GPS) al mapeo de barreras y barras intermareales, Río Grande, Tierra del Fuego, Argentina

Con el objetivo de analizar la utilidad del Sistema de Posicionamiento Global (GPS) para el levantamiento planimétrico de formas litorales se realizaron tareas de mapeos en la desembocadura del Río Grande, Tierra del Fuego. Se utilizaron dos navegadores GPS Magellan 5000 Pro, aplicando posicionamiento diferencial móvil (Fase de código). La experiencia mostró que: a) el método provee, en forma rápida y a bajo costo, una medición de las formas litorales con un error menor o igual a 5 m; b) independencia de las condiciones meteorológicas y c) posibilitaría el mapeo inmediatamente posterior a la concurrencia de olas de gran energía que modifiquen substancialmente la costa.GPS mapping profiency of litoral features was analized during a planimetric survey in the Río Grande (Tierra del Fuego, Argentina) inlet. Two GPS Magellan Nav 5000 Pro were used applying differential processing. The expenence shows that: a) the method gives rapidly, and at a low cost, a litoral landforms measurement with a ( 5 m error; b) is weather independent and c) would allow for an inmediate mapping of significative morphological changes along the coast due to the occurrence of high energy waves.Facultad de Ciencias Astronómicas y Geofísica

An orbital meteoroid stream survey using the Southern Argentina Agile MEteor Radar (SAAMER) based on a wavelet approach

Over a million individually measured meteoroid orbits were collected with the Southern Argentina Agile MEteor Radar (SAAMER) between 2012–2015. This provides a robust statistical database to perform an initial orbital survey of meteor showers in the Southern Hemisphere via the application of a 3D wavelet transform. The method results in a composite year from all 4 years of data, enabling us to obtain an undisturbed year of meteor activity with more than one thousand meteors per day. Our automated meteor shower search methodology identified 58 showers. Of these showers, 24 were associated with previously reported showers from the IAU catalogue while 34 showers are new and not listed in the catalogue. Our searching method combined with our large data sample provides unprecedented accuracy in measuring meteor shower activity and description of shower characteristics in the Southern Hemisphere. Using simple modeling and clustering methods we also propose potential parent bodies for the newly discovered showers.Facultad de Ciencias Astronómicas y Geofísica

Acuerdo externo en distancia cenital

A partir de la instalación de un termómetro digital con tres sensores en el recinto de observación de la EARG (agosto 1983), el cálculo de la refracción atmosférica puede hacerse utilizando medidas reiteradas de la temperatura del aire (Informe de trabajo presentado en la XXX Reunión de la AAA, San Juan, 1984). Igualmente pueden medirse las diferencias de temperatura "aire-instrumento" y emplear un modelo para la variación del ángulo del prisma principal ocasionada por este gradiente térmico. Ambos efectos alteran principalmente la distancia cenital verdadera de observación. En este informe se analiza el acuerdo externo en Z con una muestra de 305 grupos (1.4 años).Asociación Argentina de Astronomí

Aplicación del Sistema de Posicionamiento Global (GPS) al mapeo de barreras y barras intermareales, Río Grande, Tierra del Fuego, Argentina

Con el objetivo de analizar la utilidad del Sistema de Posicionamiento Global (GPS) para el levantamiento planimétrico de formas litorales se realizaron tareas de mapeos en la desembocadura del Río Grande, Tierra del Fuego. Se utilizaron dos navegadores GPS Magellan 5000 Pro, aplicando posicionamiento diferencial móvil (Fase de código). La experiencia mostró que: a) el método provee, en forma rápida y a bajo costo, una medición de las formas litorales con un error menor o igual a 5 m; b) independencia de las condiciones meteorológicas y c) posibilitaría el mapeo inmediatamente posterior a la concurrencia de olas de gran energía que modifiquen substancialmente la costa.GPS mapping profiency of litoral features was analized during a planimetric survey in the Río Grande (Tierra del Fuego, Argentina) inlet. Two GPS Magellan Nav 5000 Pro were used applying differential processing. The expenence shows that: a) the method gives rapidly, and at a low cost, a litoral landforms measurement with a ( 5 m error; b) is weather independent and c) would allow for an inmediate mapping of significative morphological changes along the coast due to the occurrence of high energy waves.Facultad de Ciencias Astronómicas y Geofísica

A new combined quasigeoid model in Tierra del Fuego

This work focuses on the development of a combined quasigeoid model for Tierra del Fuego province. The Equivalent Source Technique (EST) is applied together with the remove-compute-restore technique in order to combine gravity and GPS/levelling observations and to obtain a quasigeoid model. This model features an improved accuracy in relation to previous models. A discussion about the geodetic reference system is also presented. Geodetic coordinates of all stations used were transformed to TDF08 to be in accordance with the new geodetic reference frame of Argentina. After a cross validation procedure it is determined that a 5cm (r.m.s.) quasigeoid model has been achieved for the major part of the province, fulfilling the requirements for its practical use. New Global Geopotential Models (GGM) are introduced in the discussion, particularly the EGM2008 which is used for evaluation purposes. It shows a 9cm agreement after its evaluation on the levelling lines.Facultad de Ciencias Astronómicas y Geofísica

Decade of Sporadic Meteoroid Mass Distribution Indices in the Southern Hemisphere Derived from SAAMER’s Meteor Observations

We present determinations of the meteoroid differential mass index, s, using over a decade of meteor observations from the Southern Argentina Agile MEteor Radar (SAAMER). For this, we employ an autonomous statistical technique to determine this parameter from the measured radar echo amplitudes. Unlike previous studies, we examine the role of the system noise in the determination of this parameter and found that if not taken into account appropriately, the results can yield significant over estimations of the mass index. In general we found that a value of s = 2.0 represents SAAMER's results in general agreement with recent studies performed in the northern hemisphere. We explore both the index interannual and seasonal variability and, unlike previous studies, we found them to be constant, except during the presence of the Southern δ Aquariids meteor shower which is so strong that it dominates the meteor counts when present. Our study suggests that using the maximum echo amplitude for these studies is not ideal as it can be biased by many factors which make the inaccuracies larger than the precision estimated by the fitting routine. A method that results in a more direct estimate of the electron line density would be required which takes into account range, gain pattern, system noise, etc.Facultad de Ciencias Astronómicas y Geofísica

Gravity map of the Isla Grande de Tierra del Fuego, and morphology of Lago Fagnano

A complete Bouguer gravity map of the central-eastern part of the Isla Grande de Tierra del Fuego, and a general bathymetric chart of the Lago Fagnano have been realized, on the basis of a series of field geophysical surveys carried out on the Island since 1998. The regional gravity anomaly trend onshore shows a progressive negative gradient from N to S. Distinct, broadly E-W-trending gravity minima are superimposed on this regional negative gradient. They follow the main trace of the Magallanes-Fagnano fault system, which represents the western segment of the left-lateral South America-Scotia transform plate boundary. The gravity minima reflect the presence in the subsurface of restricted and elongated basins developed within the principal displacement zone of the fault system. A relative positive gravity maximum is located just at the SE corner of the Lago Fagnano, and represents the response of a partially exposed crystalline body, occupying an area 3 x 3 km wide. A 2D vertical crustal model has been constructed, combining gravity data inversion and geological information available for the central-eastern region of Lago Fagnano. The bathymetric map of the Lago Fagnano delineates the main morphological features of this 110-km-long, 7-km-wide lake, the largest of Isla Grande. The floor is divided into distinct parts, which suggests that the basin is composed of different sub-basins. In most areas, the basin floor is highly asymmetric in shape, with flat depocentral areas. The most pronounced asymmetry of the basin is seen in the eastern end of the lake, where there is also the deepest depression. The steeper slope of the basin, along the northern shore of the Lago Fagnano, also coincides with the most pronounced regional topographic gradient. The general gravimetric and morphological features of the investigated region are here discussed.Fil: Lodolo, Emanuele. No especifíca;Fil: Lippai, Horacio Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; ArgentinaFil: Tassone, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; ArgentinaFil: Zanolla, Marianela. No especifíca;Fil: Menichetti, Marco. Università Degli Studi Di Urbino Carlo Bo; ItaliaFil: Hormaechea, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin