Equipments

Radiotelescope

The RAEGE radio telescopes are azimuth/elevation turning head telescopes, reaching azimuth and elevation slew speeds of 12°/s and 6°/s, respectively. The optical design is based on a 13.2-m ring focus reflector. In its basic configuration, the observation frequency is in the range of 2–40 GHz that can be enhanced up to 100 GHz by using additional options.

The telescope is mounted on a concrete tower, which consists of two levels. The ground floor level is for electrical cabinets, and the first level accommodates the azimuth cable twister. The telescope is fully steerable. There is an azimuth axis to rotate the antenna structure along the vertical axis and an elevation axis to rotate the reflector along the horizontal axis. Furthermore, a hexapod positions the sub-reflector. The antenna is equipped with two computer control systems, one for the main axis (ACU) and one for the hexapod (HCU).

The main figures of the radio telescope are:

  • Azimuth range: +/- 270°
  • Elevation range: 0 +100
  • Main reflector diameter: 13.2 m
  • Sub reflector diameter: 1.55 m
  • Distance main reflector vertex from elevation axis: 3.270 m
  • Max. Azimuth slewing speed: 12°/s
  • Max. Elevation slewing speed: 6°/s

The optical configuration of the radio telescope is Ring Focus, which provides a high-efficiency antenna with no reflection back to the feed and no blockage of the sub-reflector.

For geodetic telescopes, it is essential to measure accurately the position of the intersection of the azimuth and elevation axes. Therefore, a concrete pillar is installed at the centre of the telescope tower, allowing the installation of a measurement system to be located at the intersection of axes and visible from the outside through openings.

Seismograph

The Trillium 120P/PA seismograph is a three-component, very wideband, low noise device. The very low band frequency is useful beyond 1000s. For these reasons, this type of seismograph is widely used for scientific studies. With a symmetrical tri-axial arrangement of the elements, this device ensures uniformity between vertical and horizontal outputs.

Gravimeter

The gravimeter is an extremely sensitive piece of equipment and for that reason it is in a separate room of the building, resting on a concrete pillar about 8m deep for contact with the bedrock. This room is always temperature and humidity-controlled.

At Santa Maria RAEGE we have a Graviton Meter. This equipment results from several improvements made to the classic relative gravimeter of LaCoste & Romberg (models G and D). The big difference is in the mechanical system, controlled by an electrical system, which simplifies most of the corrections and functions that must be applied in the records of the gravitational fields.

This gravimeter is designed to run in continuous mode. It provides a final resolution of approximately 1µGal (=10E-8 ms^-2) and can achieve 0.1µGal accuracy under ideal conditions. This resolution makes this type of gravimeter suitable for determining land tides as well as geophysical effects.

Accelerometer

The IGN has developed low-cost accelerometers known as Silex, based on MEMS technology to detect and record earthquakes with magnitudes that are perceptible by humans. A network of this equipment is implemented in areas of high seismic risk, as is the case of the island of Santa Maria. This equipment measures the acceleration of the ground recording strong movements that occur, for example, near tectonic faults. 

Hydrogen Maser

A fundamental Geodetic Station hosts at least one active hydrogen maser that is used as a frequency reference for the Station. This type of atomic clock guarantees frequency stability that we know. This being an essential feature in VLBI observations, allowing to preserve the coherence time at high frequencies. VLBI observations are not possible without this reference system of the maser system.

The maser is in a chamber isolated from the building with temperature-controlled and pressure and humidity monitored.

As VLBI is an unconnected interferometry technique, it requires the highest possible accuracy and stability in frequency patterns to maintain coherence between two remote stations over a long integration period to improve instrument sensitivity. A typical active H-maser has an Allan Variation better than 10-13, which corresponds to the typical integration time during a correlation of VLBI observations.

GNSS

A Estação RAEGE de Santa Maria tem duas estações de GNSS permanentes, integradas nas redes IGS, EUREF e Rede Regional dos Açores. A estação RAEGE equipadas com um recetor Leica GRX1200GG Pro e uma antena LEIAT504 LEIS e a Estação REPRAA (Rede Regional dos Açores) está equipada com –

GNSS receivers detect, decode, and process signals from GNSS satellites (GPS, GLONASS, GALILEO, etc.) which enable the locations of the receivers to be determined with varying degrees of accuracy.

The coordinates of these stations are calculated using highly accurate scientific software. The stations are equipped with multi-frequency geodetic receivers, capable of receiving other satellite constellations and geodetic antennas, almost all with phase centre variation calibration.

The International GNSS Service (IGS) network consists of hundreds of permanent GNSS receivers. The historical records of high-precision measurements of the receivers' location allow the study of tectonic plate movements, displacements associated with earthquakes, and the orientation of the Earth.

The permanent GNSS receivers at the Santa Maria RAEGE Station contribute to the international network (IGS), the European network (EUREF), the Spanish national network (IGN), and the Azores regional network (REPRAA). 

Meteorological Station

The weather station WXT530 that we have at RAEGE is a series of weather instruments that provide six of the most important meteorological parameters: air pressure, temperature, humidity, precipitation, wind speed, and direction through various combinations. This information is very important to complement the VLBI observations since weather changes influence the signal received at the antenna.

Radiotelescope

The RAEGE radio telescopes are azimuth/elevation turning head telescopes, reaching azimuth and elevation slew speeds of 12°/s and 6°/s, respectively. The optical design is based on a 13.2-m ring focus reflector. In its basic configuration, the observation frequency is in the range of 2–40 GHz that can be enhanced up to 100 GHz by using additional options.

The telescope is mounted on a concrete tower, which consists of two levels. The ground floor level is for electrical cabinets, and the first level accommodates the azimuth cable twister. The telescope is fully steerable. There is an azimuth axis to rotate the antenna structure along the vertical axis and an elevation axis to rotate the reflector along the horizontal axis. Furthermore, a hexapod positions the sub-reflector. The antenna is equipped with two computer control systems, one for the main axis (ACU) and one for the hexapod (HCU).

The main figures of the radio telescope are:

  • Azimuth range: +/- 270°
  • Elevation range: 0 +100
  • Main reflector diameter: 13.2 m
  • Sub reflector diameter: 1.55 m
  • Distance main reflector vertex from elevation axis: 3.270 m
  • Max. Azimuth slewing speed: 12°/s
  • Max. Elevation slewing speed: 6°/s

The optical configuration of the radio telescope is Ring Focus, which provides a high-efficiency antenna with no reflection back to the feed and no blockage of the sub-reflector.

For geodetic telescopes, it is essential to measure accurately the position of the intersection of the azimuth and elevation axes. Therefore, a concrete pillar is installed at the centre of the telescope tower, allowing the installation of a measurement system to be located at the intersection of axes and visible from the outside through openings.

Seismograph

The Trillium 120P/PA seismograph is a three-component, very wideband, low noise device. The very low band frequency is useful beyond 1000s. For these reasons, this type of seismograph is widely used for scientific studies. With a symmetrical tri-axial arrangement of the elements, this device ensures uniformity between vertical and horizontal outputs.

Gravimeter

The gravimeter is an extremely sensitive piece of equipment and for that reason it is in a separate room of the building, resting on a concrete pillar about 8m deep for contact with the bedrock. This room is always temperature and humidity-controlled.

Na RAEGE de Santa Maria dispomos de um Graviton Meter. Este equipamento resulta de várias melhorias feitas ao clássico gravímetro relativo da LaCoste & Romberg (modelos G e D).  A grande diferença está no sistema mecânico, controlado através de um sistema elétrico, o que simplifica a maior parte das correções e funções que têm de ser aplicadas nos registos dos campos gravitacionais.

This gravimeter is designed to run in continuous mode. It provides a final resolution of approximately 1µGal (=10E-8 ms^-2) and can achieve 0.1µGal accuracy under ideal conditions. This resolution makes this type of gravimeter suitable for determining land tides as well as geophysical effects.

Accelerometer

The IGN has developed low-cost accelerometers known as Silex, based on MEMS technology to detect and record earthquakes with magnitudes that are perceptible by humans. A network of this equipment is implemented in areas of high seismic risk, as is the case of the island of Santa Maria. This equipment measures the acceleration of the ground recording strong movements that occur, for example, near tectonic faults. 

Hydrogen Maser

A fundamental Geodetic Station hosts at least one active hydrogen maser that is used as a frequency reference for the Station. This type of atomic clock guarantees frequency stability that we know. This being an essential feature in VLBI observations, allowing to preserve the coherence time at high frequencies. VLBI observations are not possible without this reference system of the maser system.

The maser is in a chamber isolated from the building with temperature-controlled and pressure and humidity monitored.

As VLBI is an unconnected interferometry technique, it requires the highest possible accuracy and stability in frequency patterns to maintain coherence between two remote stations over a long integration period to improve instrument sensitivity. A typical active H-maser has an Allan Variation better than 10-13, which corresponds to the typical integration time during a correlation of VLBI observations.

GNSS

The RAEGE station in Santa Maria has two permanent GNSS stations, integrated into the IGS, EUREF, and Azores Regional Network networks. The RAEG station is equipped with a Leica GRX1200GG Pro receiver and a LEIAT504 LEIS antenna and the REPRAA station (Regional Network of Azores) is equipped with -

GNSS receivers detect, decode, and process signals from GNSS satellites (GPS, GLONASS, GALILEO, etc.) which enable the locations of the receivers to be determined with varying degrees of accuracy.

The coordinates of these stations are calculated using highly accurate scientific software. The stations are equipped with multi-frequency geodetic receivers, capable of receiving other satellite constellations and geodetic antennas, almost all with phase centre variation calibration.

The International GNSS Service (IGS) network consists of hundreds of permanent GNSS receivers. The historical records of high-precision measurements of the receivers' location allow the study of tectonic plate movements, displacements associated with earthquakes, and the orientation of the Earth.

The permanent GNSS receivers at the Santa Maria RAEGE Station contribute to the international network (IGS), the European network (EUREF), the Spanish national network (IGN), and the Azores regional network (REPRAA). 

Meteorological Station

The weather station WXT530 that we have at RAEGE is a series of weather instruments that provide six of the most important meteorological parameters: air pressure, temperature, humidity, precipitation, wind speed, and direction through various combinations. This information is very important to complement the VLBI observations since weather changes influence the signal received at the antenna.

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