Helmos Observatory - "Aristarchos" 2.3m telescope

Helmos Observatory is situated on "Neraidorachi", a mountaintop of the Helmos mountain chain in the Peloponnese. The site is 2340 m above sea level, 220 km southwest of Athens, and is one of the darkest places in continental Europe. Helmos Observatory hosts the "Aristarchos" telescope, an optical telescope designed and manufactured by the german company Carl Zeiss GmbH. The main characteristic of this telescope is its 2.3 m mirror which, combined with the super-sensitive detectors that the telescope is equipped with and the good atmospheric conditions of the site, makes it a very valuable tool for observing astronomical objects, even very faint and very distant objects located in the outskirts of the Universe. More information on the telescope and the site can be found here.

Kryoneri Observatory

Kryoneri Observatory (established in 1972) is located in the district of Corinth in the northern Peloponnese at the top of mount Kyllini, close to Kryoneri village. It is equipped with a 1.2 m Cassegrain reflector telescope manufactured and installed in 1975 by the British company Grubb Parsons Co., Newcastle. It is one of the largest telescopes in Greece, with many successful scientific observations during its long operation (scientific observations started in 1975). In 2016, the telescope was upgraded in the framework of the ESA program NELIOTA, to monitor the lunar surface for impacts of near-earth objects. More information on the telescope and the site can be found here.

Newall Telescope

The historic Newall 62.5 cm refractor is located at the Visitor Center in Penteli. The telescope was commissioned by Robert Stirling Newall (1812-1889), a wealthy Scottish engineer and amateur astronomer for his private observatory at Ferndene (Gateshead). In 1890 the telescope was donated to the University of Cambridge. In 1957 it was donated to the National Observatory of Athens. The telescope is now used as the main observational and public outreach facility of the Visitor Center.

Doridis Telescope

The Doridis telescope was built in 1902 and remained as the largest telescope of Greece for 57 years. The telescope is named after the benefactor Dimitrios Doridis, who financed its construction. It is a refractor with double achromatic lenses of 40cm diameter and has 5m focal length. Its tube is mounted on a so-called German-type equatorial mounting and it is house in a new dome not far from the Sinas building. The Doridis refractor was extensively used for observations of planets, comets, and the moon, as well as for astrometry and photometry of variable stars. Currently, the telescope is used for the purposes of education and public outreach.

Optics and Electronics Laboratories

The Optics and Electronics Laboratories began their operation in mid-2006 at the premises of IAASARS in Penteli. Both labs are equipped with all the necessary equipment (two optical tables with special isolator legs for removing vibrations, calibration lamps, laser equipment, etc.) in order to support the operation and maintenance of the 2.3m "Aristarchos" telescope. In particular, laboratory tests of scientific instruments which will be placed on the telescope, work that needs to be made before scientific instruments settle to the telescope and during their use when needed, measurements of the filters, CCD cameras and calibration lamps, installation of special computer programs to be used at the telescope or in specific instruments, design and manufacture of opto-electronic components for spectrometers and calibration systems in astronomical instruments. Also, making vacuum in CCD cameras using special pumps at regular intervals. In both labs we also perform, the design, manufacture and testing of new scientific instruments as well as the design and testing of steel sections supporting scientific instruments. Finally, we develop and upgrade operating systems for astronomical instruments.

The Athens Digisonde Portable Sounder

The Athens Digisonde is an infrastructure for remote sensing of the Earth's Ionosphere, operated by NOA in Penteli since September 2000. The Digisonde is a Digital Portable Sounder with four receiving antennas (DPS-4), spaced about one wavelength apart. Data are collected and retrieved in real time (24/7 operation) and are openly available through the main portal of the Ionospheric Group of IAASARS/NOA ( The Athens Digisonde is part of the following international networks: GIRO, ESPAS, WDC for Solar-Terrestrial Physics (RAL) and IPS/WDC. The Athens Digisonde participates systematically in cal/val campaigns for LEO satellites. For more information and access to data please visit the Athens Digisonde web portal.

DIAS system: The European DIgital Upper Atmosphere Server

The DIAS system was developed under the EC eContent Programme (2006) and delivers systematically a comprehensive set of data and products that characterize ionospheric and plasmaspheric conditions over Europe. The service was recently expanded to retrieve data from 10 European Digisondes and Ionosondes (Athens, Rome, Ebre, Arenosillo, Chilton, Juliusruh, Pruhonice, Moscow, Tromso and Sodankyla), as well as solar wind data from ACE, and supportive data from NOAA (solar and geomagnetic indices) and ROB (GNSS data). Data are collected in the DIAS backend and ingested into prediction models. The resulting products serve more than 500 registered users through the DIAS GUI, through API (on-demand services to ESA, NOAA and IZMIRAN) and through a wrapper interface (ESPAS platform).

Geomagnetic Array ENIGMA

NOA currently operates ENIGMA (HellENIc GeoMagnetic Array), an array of 3 ground-based magnetometer stations located in Trikala (Klokotos), Attiki (Dionysos) and Lakonia (Velies), Greece. ENIGMA provides measurements for the study of geomagnetic pulsations, resulting from the solar wind- magnetosphere coupling. Ground-based magnetometers have proven to be the workhorse of magnetosphere-ionosphere coupling physics. They enable effective remote sensing of geospace dynamics and therefore their importance in space weather monitoring and research is indisputable. ENIGMA is the first magnetometer station array that has ever operated in Greece and within a few years of operation has succeeded in becoming a SuperMAG contributor. SuperMAG ( is a worldwide collaboration of organizations and national agencies that currently operate more than 300 ground-based magnetometers. SuperMAG provides easy access to validated ground magnetic field perturbations in the same coordinate system, identical time resolution and with a common baseline removal approach. The purpose of SuperMAG is enable scientists, teachers, students and the general public to have easy access to measurements of the Earth's magnetic field.

Atmospheric Remote Sensing Station

Since February 2009, IAASARS has been operating a ground-based Atmospheric Remote Sensing Station (ARSS) to monitor ground solar radiation levels and aerosol pollution over the city of Athens, Greece. ARSS is located on the roof of the Biomedical Research Foundation of the Academy of Athens (37.9 N, 23.8 E) at an elevation of 130 m above mean sea level. The site is located close to the Athens city centre and 10 km from the sea. ARSS is equipped with a CIMEL CE318-NEDPS9 solar photometer for the retrieval of the aerosol optical depth at 8 wavelengths from 340 to 1640 nm, including polarization observations. The CIMEL instrument is a part of NASA's AERONET (Aerosol Robotic Network). The data are processed on a daily basis and are available at AERONET's webpage along with aerosol inversion retrievals, useful for aerosol characterization purposes (e.g. classification of Saharan dust advection, smoke or volcanic ash episodes etc). ARSS is additionally equipped with a UV-MFR instrument for radiation measurements in the UV spectral region. The instrumentation of IAASARS constitutes a state-of-the-art passive remote sensing suite for atmospheric research, the first one that ever operated in Athens with such specifications.

Meteosat Second Generation SEVIRI Ground Station System

Since 2007, the Institute has installed and has been using on a 24/7 operational basis a ground station for systematically receiving satellite imagery from the MSG-SEVIRI system maintained by EUMETSAT. The operating agreement for the collection, archiving, and exploitation for research purposes of MSG images, signed between IAASARS and EUMETSAT, was recently renewed in 2012. On an operational level, the main application of the MSG/SEVIRI ground station is the detection, monitoring and mapping of forest wildfires in near-real time (every 5 minutes) for the entire Greek territory, the briefing of the public authorities and stakeholders involved in the management and suppression of wildfires, and informing the citizens whose properties are threatened by ongoing catastrophic fire events (

X/L Band Satellite Acquisition Station

IAASARS/NOA Ground Segment has been expanded in the framework of the BEYOND project with the installation of an X-, and L-band satellite acquisition station for reception, acquisition, and processing of the direct broadcast downlinks from satellite missions including the EOS Aqua & Terra satellites (MODIS - Moderate Resolution Imaging Spectroradiometer), the NPP (VIIRS, ATMS, etc), the future NPOESS, the NOAA, the FYI, and the MetOP satellites. The IAASARS/NOA Ground Segment is equipped with the proper processing, archiving, and cataloguing facilities for handling in real time image data from the missions above, as well as the future Copernicus satellite missions (Sentinels) through ESA's Ground Segment. Those Ground Segment facilities foster the development of a wide range of environmental monitoring services, such as: aerosol pollution indexes assessment, dust and volcanic ash alerts, smoke dispersion forecasts, wildfire detection and monitoring, geo-hazard activity monitoring and assessment (earthquakes/volcanoes/landslides), and urban heat Island mapping.

Mobile Lidar EMORAL

Since 2011, IAASARS has been operating the mobile lidar system EMORAL in collaboration with the European Space Agency (ESA). EMORAL is a portable depolarization - Raman lidar, mounted in a minivan, capable of detecting polar and cross-polar signal at 355nm, total linear polarized signal at 532nm and nitrogen's Raman return at 387nm. EMORAL is capable of providing aerosol extinction, backscatter and depolarization vertical distributions, as well as aerosol microphysical properties utilizing innovative inversion techniques. The system currently operates in campaign mode, participating in satellite validation activities and aerosol characterization experiments like HYFLEX (Verification of the Hyperspectral Plant Imaging Spectrometer), ACEMED (Evaluation of CALIPSO's aerosol classification scheme over Eastern Mediterranean), ChArMEx (The Chemistry-Aerosol Mediterranean Experiment), ARGON (Aerosol and TRace Gases Observational Campaign at NEO).

PollyXT lidar for atmospheric research

Since 2015, IAASARS operates the advanced PollyXT portable lidar system, developed by IAASARS and TROPOS researchers. The PollyXT is an automated multi-wavelength (1064, 532 and 355nm) backscatter/Raman and polarization lidar. The system combines the latest EARLINET lidar quality standards in a stand-alone design. It is equipped with two (2) receiver units; one (1) far-range and one (1) near-range telescope. It is capable of performing measurements with very high vertical and temporal resolution, for the following physical quantities: a) particle backscatter coefficient at 355, 532 and 1064nm, b) particle extinction coefficients at 355 and 532nm, c) volume/particle linear depolarization ratio at 355 and 532nm, d) near-range backscatter and extinction coefficients at 532nm, e) water vapor at 407nm. This innovative setup provides autonomous and quality-assured vertically resolved measurements of aerosol and cloud properties. The system has so far been successfully deployed on the Athens JRA1 and Cyprus BACCHUS campaigns, while it is currently in the process of being integrated into a custom-built container.

Computer Infrastructure

The IAASARS LAN network is part of the extended NOA network. The IAASARS network is connected to the internet via the "Greek Research and Technology Network" at a speed of 1 Gbps. The IAASARS LAN operates at 100/1000 Mbps (wireless, fiber optic and UTP wiring) and uses four CISCO routers and six CISCO switches. It serves about 200 computing and peripheral units. Helmos Observatory is connected to the wide area network through an optical fibre and a wireless (antenna) connection which serves as a backup. The computer center of the Institute includes a linux cluster with 32 processors and 64GB total memory. It is used extensively for research purposes by NOA staff but also from outside.

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National Observatory of Athens
Institute for Astronomy, Astrophysics, Space Applications & Remote Sensing
Vas. Pavlou & I. Metaxa, 15236 Penteli, Greece