An Upgrade for the international Radio Telescope LOFAR

05.07.2024

The last regular observation cycle of the first generation of the LOFAR radio telescope ended on May 31, 2024. The radio telescope will be upgraded over the next two years. On June 10, 2024, the founding of the LOFAR European Research Infrastructure Consortium (LOFAR ERIC) was celebrated.

When you work at the Thuringian State Observatory you are familiar with the LOFAR field. The radio telescope is located behind the 2-Meter Alfred-Jensch-Telescope. It consists of two antenna fields: one for the low band antennas, ranging between 10 and 90 MHz, and one for the high band antennas, ranging between 110 and 250 MHz.

The LOFAR station in Tautenburg shortly after it was built. Photo: TLS / Michael Pluto
The Tautenburg station of the European radio telescope LOFAR (Low Frequency Array) was put into operation in 2010. LOFAR began as a national project in the Netherlands and now comprises more than 50 stations across Europe (as of 2024). This joint project fundamentally advanced low-frequency radio astronomy and led to a wealth of scientific publications.

LOFAR is the world's first radio telescope that made it possible to create detailed maps of the sky at very low radio frequencies for the first time. With these maps, scientists can, for example, study the effects of black holes in distant galaxies and trace the history of star formation in the development of the universe.

Researchers at the Thuringian State Observatory played a leading role in data processing for the "LOFAR 2 Meter Sky Survey". Around half of the data collected for this survey was processed by Dr. Alexander Drabent, scientist at the Thuringian State Observatory.

The station in Tautenburg was the second international station outside the Netherlands. The first radio sky image with the Tautenburg LOFAR station was recorded back in April 2009. After 14 years of observation, it is now time for further development.

More detailled observations

Over the next two years, the radio telescope will be transformed to "LOFAR 2.0". The electronics will be improved so that even more precise observations can be made. Dr. Alexander Drabent explains, how: "The processing capacity will be increased so that the radio telescope will be able to process more signals simultaneously than before." For this purpose, the hardware is being upgraded.

Each LOFAR station consists of two antenna arrays. Until now, it was possible to observe with either one or the other field. In the future, it should be possible to receive radio signals with both arrays at the same time.

Joint further development under a new structure

The radio telescope is not only getting a technical upgrade, the legal form has also been adapted to the international research project. LOFAR was previously organized as a Dutch foundation. At the beginning of 2024, LOFAR was transferred to an independent legal form: a consortium for a European research infrastructure, known as the European Research Infrastructure Consortium (ERIC).

Reception at Dwingeloo, Netherlands, to celebrate LOFAR ERIC, Photo: ASTRONThe European Commission decided to establish LOFAR as a European research infrastructure consortium due to the Europe-wide importance of the radio telescope. The LOFAR ERIC Council officially founded LOFAR ERIC on January 22, 2024, following several years of preparations to make the international LOFAR telescope fit for the future with the new European legal form.

"The new organizational structure as European Research Infrastructure Consortium reflects the participation of many European countries and enables them to further develop LOFAR together," explains Professor Dr. Matthias Hoeft, Deputy Director of the Thuringian State Observatory. He coordinates the German LOFAR consortium. This means that the Thuringian State Observatory represents German scientific interests in the LOFAR ERIC Council as so-called Representing Entity.

On June 10, 2024, Professor Dr. Hoeft, and the Director of the Thuringian State Observatory, Professor Dr. Markus Roth, attended the founding ceremony of LOFAR ERIC in Dwingeloo. The reception took place at the headquarters of the international radio telescope at ASTRON in the Netherlands.

Active cooperation with astrophysicists from Uganda

10.06.2024

The Thuringian State Observatory has been cooperating with universities in Uganda for many years. In May, two astrophysicists from the African country visited again. One of them knows the Tautenburg Observatory very well because he did his Ph.D. work there.

Dr. Benard Nsamba and Dr. Cosmos Dumba, both from Uganda, came to visit the Thuringian State Observatory (TLS) in May 2024. Dr. Nsamba is a lecturer and Branco Weiss Fellow at the Department of Physics at Kyambogo University in Uganda's capital Kampala. Dr. Dumba is a lecturer at Mbarara University of Science and Technology in the city of Mbarara, Uganda.

Cosmos Dumba, Mbarara University, and Johannes Winkler, head of the mechanics workshop at Thuringian State Observatory (Foto: TLS)
Dr. Dumba came to the Thuringian State Observatory in 2014 to do his doctoral thesis in the field of radio astronomy. His research work was supervised by Professor Dr. Matthias Hoeft, Deputy Director of the Thuringian State Observatory. After he received his doctorate from Friedrich Schiller University Jena in 2019, Dr. Dumba went back to Uganda and initiated the cooperation with TLS.

Dr. Nsamba's research focus is asteroseismology. He received his doctorate from the University of Porto in Portugal. At Kyambogo University in Uganda, he heads a group that is a partner of the Max-Planck-Institute for Astrophysics in Garching.

The cooperation between the universities in Uganda and the Thuringian State Observatory is very active. Dr. Eike Günther, a scientist at the Thuringian State Observatory, is a guest lecturer there. He also was the Ph.D. advisor for Priscilla Muheki, wo was the first student to receive a Ph.D. in Astronomy from a Ugandan university. In addition, several TLS scientists gave lectures at the first “Sub-Saharan Africa Advanced Astronomy Summer School” in 2022, organized by Dr. Dumba and Dr. Nsamba.

Aiming to expand cooperation

During this year's visit, Dr. Nsamba and Dr. Dumba talked with researchers at TLS how they could intensify their scientific collaboration. Kyambogo and Mbarara Universities are in the process of expanding their previously small astronomy departments. The scientists discussed which joint research projects can be tackled and whether a scientific exchange between students and scientists is possible.

Dr. Cosmos Dumba gave an online presentation for students at Mbarara University of Science & Technology during his visit to Tautenburg. As part of his lecture „Observational Techniques in Astronomy“, he explained how the different operating modes of the 2-meter universal telescope at the Thuringian State Observatory work. The telescope can operate in both Coudé and Schmidt mode.

„It's very motivating for the students when I can show them the various observation techniques using the 2-meter telescope in Tautenburg as an example“, comments Dr. Cosmos Dumba. He plans to offer such virtual lectures on a regular basis - with the support of scientists at TLS.

ESO signs agreement for ANDES instrument on the ELT

06.06.2024

ESO has signed an agreement with an international consortium of institutions for the design and construction of ANDES. The Thuringian State Observatory is part of the international consortium. ANDES stands for "ArmazoNes high Dispersion Echelle Spectrograph".

ANDES is a powerful spectrograph that will be installed on ESO's Extremely Large Telescope (ELT). A spectrograph splits light into its component wavelengths. Astronomers use it to determine important properties about astronomical objects, such as their chemical compositions. The instrument will have a record-high wavelength precision in the visible and near-infrared regions of light. When working in combination with the powerful mirror system of the ELT, it will pave the way for research spanning multiple areas of astronomy.

Researchers will use the instrument to search for signs of life on extrasolar planets and to identify the very first stars in the universe. In addition, astronomers will be able to use ANDES data to test whether the fundamental constants of physics vary with time and space. Its comprehensive data will also be used to directly measure the acceleration of the Universe’s expansion, one of the most pressing mysteries about the cosmos.

The agreement was signed by ESO’s Director General, Xavier Barcons, and by Roberto Ragazzoni, the President of Italy’s National Institute for Astrophysics (INAF), the institution leading the ANDES consortium.  The international consortium is made up of numerous research institutes in 13 countries. In addition to the Thuringian State Observatory, the German members of the consortium include the Leibniz-Institut für Astrophysik Potsdam (AIP), the Institut für Astrophysik und Geophysik, Georg-August-Universität Göttingen (IAG), the Atmospheric Physics of Exoplanets Department, Max-Planck-Institut für Astronomie Heidelberg (MPIA), the Zentrum für Astronomie, Universität Heidelberg (ZAH), and the Hamburger Sternwarte, Universität Hamburg (UHH).

"ANDES enables cutting-edge research in astronomy. I am delighted that the Thuringian State Observatory is part of the international consortium. This opens the door for us to continue making our contribution to important astronomical discoveries in the future", says Professor Dr. Markus Roth, Director Thuringian State Observatory.

This is how the ELT will look like. Credit: ESO
ESO’s ELT is currently under construction in the Atacama Desert of Northern Chile. Its main mirror will have a diameter of 39 meters and consist of 798 hexagonal segments. The ELT is scheduled to go into operation by 2030. It will be the largest optical telescope in the world and will usher in a new era of ground-based astronomy.

The ANDES project is developed by an international consortium composed of research institutes in 13 countries. They are:

• Brazil: Board of Stellar Observational Astronomy, Universidade Federal do Rio Grande do Norte, Observatório Nacional
• Canada: Observatoire du Mont-Mégantic and the Trottier Institute for Research on Exoplanets, Université de Montréal
• Denmark: Instrument Centre for Danish Astrophysics on behalf of Niels Bohr Institute, Aarhus University, Danmarks Tekniske Universitet
• France: Centre National de la Recherche Scientifique (CNRS) on behalf of Observatoire de la Côte d’Azur, Université Côte d’Azur (LAGRANGE), Laboratoire d’Astrophysique de Marseille, Aix-Marseille Université, Centre National d’Etudes Spatiales (LAM), Institut de Recherche en Astrophysique et Planetologie, Université Toulouse III-Paul Sabatier (IRAP), Institut de Planétologie et d’Astrophysique de Grenoble, Université Grenoble-Alpes (IPAG), Laboratoire Univers et Particules de Montpellier, Université de Montpellier (LUPM), Institut d’Astrophysique de Paris, Sorbonne Université (IAP), Laboratoire de Météorologie Dynamique, Ecole Normale Supérieure, Ecole Polytechnique, Sorbonne Université (LMD)
• Germany: Leibniz-Institut für Astrophysik Potsdam (AIP), Institut für Astrophysik und Geophysik, Georg-August-Universität Göttingen (IAG), Atmospheric Physics of Exoplanets Department, Max-Planck-Institut für Astronomie Heidelberg (MPIA), Zentrum für Astronomie, Universität Heidelberg (ZAH), Thüringer Landessternwarte Tautenburg (TLS), Hamburger Sternwarte, Universität Hamburg (UHH)
• Italy: INAF, Istituto Nazionale di Astrofisica (Lead Technical Institute)
• Poland: Nicolaus Copernicus University in Torun
• Portugal: Instituto de Astrofísica e Ciências do Espaço (IA) at Centro de Investigaço em Astronomia/Astrofísica da Universidade do Porto (CAUP), Instituto de Astrofísica e Ciências do Espaço at Faculdade de Ciências da Universidade de Lisboa, Associação para a Investigação e Desenvolvimento de Ciências (FCiências.ID)
• Spain: Instituto de Astrofísica de Canarias (IAC); Consejo Superior de Investigaciones Científicas (CSIC, Spain) on behalf of Instituto de Astrofísica de Andalucía (IAA), Centro de Astrobiología de Madrid (CSIC-INTA)
• Sweden: Lund University, Stockholm University, Uppsala University
• Switzerland: Département d’Astronomie, Université de Genève; Weltraumforschung und Planetologie, Physikalisches Institut, Universität Bern
• United Kingdom: Science and Technology Facilities Council, United Kingdom Research and Innovation on behalf of Cavendish Laboratory & Institute of Astronomy, University of Cambridge; UK Astronomy Technology Centre; Institute of Photonics and Quantum Sciences, Heriot-Watt University
• USA: Department of Astronomy, University of Michigan

Learn more about ANDES on ESO's website.

Amateur and professional astronomers keep an eye on minor planets together

30.05.2024

The „Small Planets“ group of the association Vereinigung der Sternfreunde e.V. (VdS) visited the Thuringian State Observatory in Tautenburg on May 26, 2024,. The observation of so-called “Near Earth Objects” is a research focus there. We explain what these Near Earth Objects are and why they are observed.

From May 24 to 26, 2024, 35 members of the “Small Planets” section of the Vereinigung der Sternfreunde e.V. met for their annual conference in Jena and Tautenburg. The VdS was founded in 1953 and is – according to their own description – the largest astronomical association in the German-speaking world with around 4,000 members.

Foto: TLS
On Saturday, May 25, the participants listened to presentations in the Senate Hall of the Friedrich Schiller University in Jena. The stargazers discussed observation techniques and methods, the analysis of star occultations by transiting minor planets, measurements with robotic telescopes, how to find new asteroids with amateur equipment and what to do if an object is on a collision course towards Earth.

On Sunday, 26 May, Dr. Bringfried Stecklum, astronomer at the Thuringian State Observatory and coordinator of small planet observations, reported on the history of the Thuringian State Observatory and its many years of experience in tracking down asteroids. He showed the 2-meter Alfred Jensch telescope, other observation facilities such as the LOFAR telescope, the solar laboratory and the plate archive. With the world's largest Schmidt camera, the Alfred Jensch Telescope is the longest-serving telescope in the world in the field of observing minor planets.

What are minor planets?

Our solar system is populated by a vast number of smaller bodies - minor planets or asteroids. Such minor planets are not always just lumps of rock. Their inner structure can be very different. In technical jargon, loosely bound objects are referred to as “rubble piles” or even “flying sand banks”. In most cases, these are former comets whose ice has evaporated during many passes by the sun.

They all have one thing in common: they move in an orbit around the sun. It is important to know the orbit of these minor planets as precisely as possible, as many of them cross the Earth's orbit. And that could be dangerous.

Productive collaboration between amateur and professional astronomers

For some years now, special sky surveys have been carried out to find all Near Earth Objects larger than 100 meters because the orbits of these bodies can change and they could collide with Earth. However, the sky surveys provide so many new objects that their classification and orbit monitoring is only possible with the support of amateur astronomers.

The Minor Planet Center (MPC) currently estimates the total number of discovered minor planets at around 1.3 million (as of May 2024). The Minor Planet Center at the Smithsonian Astrophysical Observatory is the official institution that collects, evaluates and publishes data on minor planets and comets. It operates under the auspices of the International Astronomical Union (IAU).

When professional or amateur astronomers observe minor planets, they send the results of their observations, i.e. the coordinates and brightness of the object at the relevant time, to the Minor Planet Center. Amateur astronomers usually observe brighter objects, while telescopes with a larger diameter, such as the Alfred Jensch Telescope in Tautenburg, select fainter objects.

The Thuringian State Observatory has been involved in the classification and monitoring of Near Earth Objects since 2010. Continuous measurements of the celestial position of newly discovered and known near-Earth asteroids increase the accuracy of their orbits. This makes it easier to assess whether a new object is close to Earth or not, or whether the danger posed by a known asteroid has increased or decreased. With an average of 6,000 measurements per year, the Thuringian State Observatory is now one of the most productive observatories in Europe for this activity.

Why watching a total solar eclipse is so special

14.05.2024

A total solar eclipse, like the one that was visible over North America on April 8, 2024, is one of the most magnificent events we humans can observe from Earth. Why? Because for a brief moment it vividly shows us our place in the universe. We can watch as the moon moves in front of the sun, as the sunlight dims, as the sun "disappears" for a short time in the middle of the day and as the moon then continues on its path.

We were in Texas on April 8, 2024 to observe the total solar eclipse. In conversations with acquaintances, friends or strangers, we often heard that many perceived the chance to see a solar eclipse "on their own doorstep" as nothing special at all. A misconception! In this report, we explain what is so great about such an event. Experiencing a total solar eclipse is great, a little eerie and, for some, spiritual. The risk of addiction is high: anyone who has ever seen a total solar eclipse will want to repeat the experience.

What you can experience during a solar eclipse

Before and during a total solar eclipse, you can experience many sensory impressions and make observations that you would otherwise not be able to see.

A very peculiar light

During a solar eclipse, the moon moves further and further in front of the sun and gradually obscures its light. This can be clearly seen in the minutes shortly before totality, before the moon completely covers the sun. The human eye perceives that the light changes in the middle of the day. The intensity decreases, the light has a different hue. If you didn't know that a solar eclipse was taking place, this change in light could be very eerie. The strange light is one of the most striking features of a solar eclipse (apart from the darkness during totality).

The corona of the sun

Photo: Evans Caglage, Dallas, Texas
The corona is an impressive sight during a total solar eclipse. This is the hot, thin outer atmosphere of the sun, which is only visible to the eye during a total solar eclipse. Its temperature is around two million degrees Celsius.

The expansion of the corona depends on the 11-year cycle of the sun's magnetic activity. During the so-called solar maximum, magnetic activity is high and the corona is large. This was the case on April 8, 2024, as we are currently in the middle of a fairly strong solar maximum.

Prominences: When the sun has pink spot

Between the visible solar disk and the corona lies the chromosphere with a temperature of 10,000 Kelvin. The chromosphere contains so-called prominences. These are hot gases that float in the solar atmosphere due to magnetic fields. Prominences usually consist of hydrogen gas, which glows in a beautiful pink to reddish color. During a total solar eclipse, the moon covers the sun's disk and gives us a rare glimpse of the sun's chromosphere.

During the solar eclipse on April 8, the sun showed a huge prominence in the south. At first glance, this looked like a small pink pimple. It is rare to see a prominence with the naked eye. Most can only be seen with binoculars. This prominence was about the size of the planet Saturn, which is why it was visible to the naked eye. Photo: NASA / Keegan Barber

The shadow of the moon

If you are in an open field during a solar eclipse when the sky is clear, you can see the core shadow of the moon racing towards you at a speed of 2,500 km/h. This racing shadow can look quite menacing - and impressive. This speeding shadow can look quite menacing - and impressive.

A sunset - but in 360 degrees on the horizon

After a normal sunset, you can see a glow of light on the western horizon. During the total solar eclipse, we saw this glow all around us on the horizon. Another difference to a daily sunset: after the sun has set, the sky is still relatively bright for some time. During a solar eclipse, the moment the moon covers the sun, it is as if someone has turned off the sun's light switch.

Caution: Only observe the sun with special glasses

Please never look at the sun without special eye protection for observing the sun. There are glasses for observing a solar eclipse. They have a film that protects your eyes. Only during the short phase of a total solar eclipse, when the moon completely covers the sun, can you look directly at the sun.

Please also take care when using a camera, telescope or binoculars: Always use a special solar filter placed over the front of the optics or in front of the lens. You can get serious eye damage if you look at the sun with a camera, binoculars or telescope without a special filter.

If you have the opportunity to observe a total solar eclipse, seize it! Did you know? Modern solar telescopes and instruments can create an artificial solar eclipse so that the sun's corona can be studied. From such systematic studies, researchers can learn a lot about the physical processes that lead to solar storms. Research into the sun is one of the focal points of research at the Thuringian State Observatory.

Author: Artie Hatzes

Aurora visible in Thüringen

11.05.2024

Northern lights — aurora borealis — were visible last night in Europe. Many people around Germany posted pictures of the aurora that was visible around midnight between Friday and Saturday. At the Thuringian State Observatory (TLS) in Tautenburg, the Northern Lights made observations by astronomers difficult. "The sky became so bright that most of the stars disappeared. Even a bright star like Beta Lyrae was barely visible, while fainter stars were lost in the glare," reported Dr. Eike Günther, researcher at TLS.

The northern lights originate from flares on the sun. These can emit not only light, but also charged particles. These charged particles hit the magnetic field of the Earth and penetrate along the field lines into the Earth's high atmosphere and thereby stimulate it to glow. This is how we see northern lights.

Our cloud monitoring camera recorded the sky during the entire night, showing the aurora developing (Video).

Green and pink colors were visible.

(Image taken with smartphone from Tautenburg, credit: Eike Guenther)

Ursa Major constellation wrapped into northern lights seen from  downtown Göttingen (Credit: Patrick Gaulme)

A new method to observe winds on planet Jupiter

15.04.2024

A team of scientists managed to draw the first map of atmospheric circulation of the planet Jupiter with the Doppler method.

Jupiter, the largest planet in our solar system, is famous for its brownish-white storm bands and its large red spot. The wind bands race around the planet in an easterly and westerly direction and reach high speeds of up to 500 kilometers per hour. An international team of astronomers, including Patrick Gaulme, astronomer at the Thuringian State Observatory in Tautenburg, has now produced the first map of these winds using the Doppler method.

What wind speeds prevail on Jupiter? Until now, astronomers have used images of the gas planet's cloud structures taken at different time intervals to answer this question. They calculate the wind speeds from the changes in the images. However, this method has its limits. "The clouds change or disappear. This affects the measurements," explains François-Xavier Schmider, Research Director at the Observatoire de la Côte d'Azur (OCA) in France who led the research project.

Another difficulty: The images allow scientists to calculate the speed of the winds in an east-west or west-east direction, but give poor results in a north-south or south-north direction. The reason is, simply put: The bands on Jupiter have different altitudes, and clouds structures are separated from one band to the next. Also, cloud tracking cannot measure the vertical motion in a planet’s atmosphere. Therefore, it is not known, how heat and chemical elements are transported from the inside to the outside of the planet.

Measuring atmospheric circulation with the Doppler method

Instead of relying on cloud images of Jupiter, Schmider's research team uses the Doppler method to observe the atmospheric circulation of the gas planet. The Doppler effect can be used to measure how the frequency of a light or sound wave changes when its source moves relative to the observer. If the source moves towards the observer, the waves arrive at the observer at shorter intervals. If the source moves away, the distances between the waves increase.

Patrick Gaulme, scientist at the Thuringian State Observatory, is part of the international research team that observed the atmospheric circulation on the planet Jupiter using the Doppler method. He describes how the researchers proceeded: "A Doppler imager is mounted on each of three telescopes in Japan, in France and in the USA. Together, these telescopes form the JOVIAL network. The Doppler imager can be used to create an image of the planet together with its Doppler velocity map by tracking the displacement of the spectral lines of sunlight reflected from Jupiter." From the shift of the spectral lines, the speed of the atmospheric motions can be deduced.

After the team had observed for around 80 hours with the instrument at one of the three telescopes, the Dunn Solar Telescope in Sunspot, New Mexico, USA, the researchers were able to create a complete zonal velocity map of the planet Jupiter. This is the first time that such a map is obtained with such a technique for any of the giant planets. “It is stunning. I particularly enjoy seeing the great red spot standing apart. And more generally, watching something that no one has done before. Scientifically speaking, the zonal wind map shows an excellent agreement with results obtained by cloud tracking, which validates the technique, and allows us to move forward”, says Patrick Gaulme.

The team has published the results of its research in the scientific article "Three-dimensional atmospheric dynamics of Jupiter from ground-based Doppler imaging spectroscopy in the visible"in the The Planetary Science Journal. The preprint of the paper is accessible under this link: https://ui.adsabs.harvard.edu/abs/2023arXiv231216888S/abstract

Both images were obtained from data recorded with the JOVIAL/JIVE instrument at the Dunn Solar Telescope in Sunspot, New Mexico.

The Dunn Solar Telescope tower at Sunspot, New Mexico, @Patrick Gaulme, for editorial purposes only

The Thuringian State Observatory

The Thuringian State Observatory Tautenburg (TLS) is a research institute funded by the Free State of Thuringia, Germany. It conducts basic research in astrophysics. Researchers at TLS use various telescopes throughout the world for their observations of galaxies, stars, the sun, gamma ray bursts, and extrasolar planets.

The Thuringian State Observatory uses and operates the 2-meter Alfred Jensch Telescope for observations in the optical spectral range and a station of the European Low Frequency Array Radio Telescope (LOFAR). It is also building a solar lab to develop a prototype of an automated telescope for the continuous observation of the sun.

Contact

We are happy to answer your questions:

Patrick Gaulme

Markus Roth

Bauhaus - Tautenburg: When Art Meets Science

09.04.2024

On February 22, we had the chance of welcoming PhD students in Art and Design from the Bauhaus University in Weimar, led by Prof. Alexandra Toland. The goal of this first meeting between the two Thuringian institutes was to get to know each other, with the idea of fostering future collaborations between art students and scientists.

The visit started with a tour of the 2m-Alfred Jensch telescope by Eike Guenther and an explanation of the LOFAR radio telescope by Alexander Drabent. Then, roundtable conversations organized by Harriet von Froreich (Bauhaus University) and Patrick Gaulme (TLS) gathered about 15 scientists and 10 art researchers to exchange ideas across disciplines regarding questions of time, distance, types of data, and the challenges and joys of developing methods in practicing research. The meeting was followed by a get together. Next visit is scheduled in June, hoping for clear skies to see the telescope at work during a short near-solstice night.

What solar physicists can learn from the solar eclipse.

07.04.2024

A total solar eclipse is a spectacular natural event. The moon moves between the sun and the earth, blocking our star. It gets dark in the middle of the day, and the night sky becomes visible. Millions of people will observe this event on April 8, 2024, in North America. Professor Dr. Markus Roth, Director of the Thuringian State Observatory, explains why the solar eclipse of 2024 is so special.

A total solar eclipse is an impressive natural spectacle. On April 8, 2024, the sun will darken in a roughly 180-kilometer-wide strip across Mexico, the United States, and Canada. Why is this solar eclipse so special?

Quelle: Friedrich-Schiller-Universität / Annegret GüntherMarkus Roth: After 2017, this solar eclipse is the second one to occur on the North American continent in a short time. The solar eclipse on April 8 is visible in a wider strip than seven years ago. Additionally, the duration of the solar eclipse is between slightly over 3 minutes to 4.5 minutes, depending on the observation location, which is quite long. In comparison, the solar eclipse on August 11, 1999, visible in Germany, lasted just over two minutes.

Currently, the sun is at the peak of its activity. This means the probability of sunspots is quite high. Sunspots are strong magnetic field poles and occur particularly frequently every eleven years. Accordingly, the sun's corona, which becomes visible during a solar eclipse, could appear very structured.

Interestingly, the comet 12P/Pons-Brooks will also be in the daytime sky on April 8. Although it is too faint to be seen with the naked eye during the eclipse, it would be visible with a telescope. However, caution must be taken not to accidentally look into the sun with the telescope or binoculars.

Millions of people will observe the celestial spectacle and hope that the sun will provide a spectacular show. You are solar physicists. What scientific insights do researchers gain from such an event?

Roth: NASA will send the WB-57 high-altitude research aircraft along the path of the solar eclipse. A research project will capture images of the solar eclipse from an altitude of 50,000 feet above the Earth's surface. By capturing images above most of the Earth's atmosphere, researchers aim to discern new details of structures in the middle and lower corona. NASA's WB-57 will also carry instruments to learn more about the temperature and chemical composition of the corona and coronal mass ejections.

With modern solar telescopes and instruments, a solar eclipse can also be artificially and continuously produced, allowing the solar corona to be continuously studied. From such systematic studies, much can be learned, for example, about the physical processes that lead to coronal mass ejections on the sun, often also called solar storms.

What have scientists learned from previous solar eclipses?

Roth: In the past, an important insight was the confirmation of the general theory of relativity. In 1919, it was demonstrated that light from stars is deflected by the gravitational effect of the sun, as calculated by Albert Einstein beforehand.

Furthermore, in the past, solar eclipses have been used to determine the temperature, composition, and magnetic field in the solar corona. The corona is the outermost layer of the solar atmosphere, which is usually overwhelmed by the sun, meaning that measurements of these physical quantities were otherwise not possible.

What impact does a solar eclipse have on the Earth?

Roth: A solar eclipse has no noticeable impact on the Earth. There may be slight temperature changes due to the darkening. Also, it is expected that the animal world may react with surprise to the sudden onset of night.

Thuringian State Observatory Achieves Milestone in Construction of New Spectrograph PLATOSpec

04.04.2024

The Thuringian State Observatory Tautenburg is part of a consortium building the high-resolution spectrograph PLATOSpec. This instrument will be mounted on a 1.52-meter telescope at the European Southern Observatory (ESO) in La Silla, Chile, during the course of 2024. An important milestone has now been reached for the project: a new front-end has been installed on the telescope, and the calibration unit has been installed.

The workshops of the Thuringian State Observatory have developed, built, and tested the calibration unit for the spectrograph PLATOSpec. At the end of March 2024, it was mounted on the 1.52-meter telescope of the ESO in La Silla, Chile, together with a new front-end.

The calibration unit serves as a reference for the telescope's observations. For this purpose, the spectrum of a thorium-argon lamp is used, whose spectral lines are already known. The spectrograph PLATOSpec will desperse the starlight captured by the telescope into a spectrum. This spectrum is then compared with that of the thorium-argon lamp. This provides researchers with a wavelength reference point. Additionally, an iodine cell is used for calibration. With the spectrum produced by this iodine cell, the radial velocity (Doppler shift) of a star can be measured very accurately.

The front-end connects the spectrograph to the telescope. It was built by the Czech company TopTech, Turnov. The Thuringian State Observatory, as a partner of the PLATOSpec consortium, commissioned, supervised, and financed the construction of the front-end.

The calibration unit and the front-end are prerequisites for connecting the PLATOSpec instrument to the 1.52-meter telescope. The spectrograph PLATOSpec is still under construction. PLATOSpec will be a state-of-the-art echelle spectrograph with high spectral resolution, covering the spectral range from 350 to 700 nanometers. PLATOSpec will support satellite missions TESS and PLATO with ground-based follow-up observations. The aim of these missions is to find planets around stars other than the Sun, known as extrasolar planets.

The PLATOSpec instrument is being built by a consortium of three institutes. The main partners of the consortium are the Astronomical Institute ASCR in Ondrejov, Czech Republic, the Thuringian State Observatory, Tautenburg, Germany, and the Pontificia Universidad Católica (PUC) de Chile, Santiago, Chile. The contribution of the Thuringian State Observatory to PLATOSpec was financed by the Thüringer Aufbaubank with funds from the research promotion program of the state of Thuringia.

Asteroid 2024 BX1 observed at the TLS shortly before its impact near Berlin

06.02.2024

The time around the full moon is actually not suitable for astrophotography. Nevertheless, the night of January 20th to 21st, 2024 had a surprise in store for Dr. Stanislav Melnikov and his colleagues. He carried out observations for the ``Near-Earth Asteroid program´´. The sky was already so bright that faint asteroids were barely visible. Thus, the researcher was pleased when a new object named Sar2736 suddenly appeared on the target list. Its brightness and speed suggested it was close to Earth. Dr. Bringfried Stecklum, who followed the measurements via the Internet and processed the images, advised him to quickly observe the object. However, the first attempt at around 11:30 p.m. failed. The replacement camera, which had to be used since TAUKAM was under repair, did not capture the asteroid with its smaller field of view. A little later more precise coordinates arrived and Dr. Melnikov tried again. This time he took six images, which were immediately evaluated (Fig. 1). An orbit is routinely calculated from the determined positions and those already known in order to detect false identifications and other problems. Dr. Stecklum became speechless when the FindOrb program used for this purpose predicted that the asteroid would hit Earth in about an hour (Fig. 2). In addition, the coordinates of the impact site suggested that this would happen in the northern central part of Germany. Normally, this would be a cause for concern, but in this case there was no reason for it. Using the typical reflectivity of asteroids and the measured brightness, FindOrb calculated a diameter of about one meter. For such a small object, part of the mass would burn up when it entered the atmosphere, and the rest would burst. Therefore, there was no danger. A third attempt to photograph Sar2736 with the TLS telescope was unsuccessful - the object was now traveling too fast. A little later there were first reports of the spectacular light phenomenon of a bolide or fireball that fell west of Berlin near Nennhausen (Havelland).

A total of 14 stations reported positions to the Minor Planet Center (MPC), which gave the object the official name 2024 BX1. The TLS was third in the order. 2024 BX1 is the eighth asteroid discovered within 24 hours of its impact. Its discoverer, Krisztián Sárneczky, from the Konkoly Observatory, had already identified two. Various search parties have now managed to find fragments of the asteroid (meteorites) (MAZ). These suggest that 2024 BX1 was not a primitive asteroid, but came from a body whose internal structure is similar to that of Earth. It may have split off from Vesta, the largest asteroid in the solar system. The rare finds promise valuable information about the history of the formation of the solar system.

Obituary Professor Dr. Josef Solf

02.02.2024

The Thuringian State Observatory mourns its former director Professor Dr. Josef Solf, who passed away on December 31, 2023, just a few weeks before his 90th birthday, in Jena.

Josef Solf had a significant impact as a scientist and institute director in Heidelberg and Tautenburg. During his time in Heidelberg at the Max Planck Institute for Astronomy, he developed spectroscopic instrumentation for the telescopes at the newly emerging German-Spanish Astronomical Center on Calar Alto. With them, he achieved recognized scientific success in the field of bipolar phenomena in star formation and development. As director of the Thuringian State Observatory, he contributed to the expansion of the institute and the modernization of the 2-meter Alfred Jensch telescope and its instrumentation.

Josef Solf was born on February 5, 1934, in Worbis in the Eichsfeld region and grew up there with his five younger brothers in "Solf's Mill." His father was a very influential figure in his life. Early on, he sparked numerous interests in him – in mill technology, music, religion, photography, philosophy, and physics. He attended boarding school in Heiligenstadt, where he graduated in 1952 with a humanistic diploma. He then began studying mathematics at the University of Jena. Driven by his big question "Am I finished yet?" he changed direction and studied philosophy, theology, and art history from 1953 to 1962 at the Jesuit universities in Berlin, Frankfurt, and Munich. As his question remained unanswered and the curiosity to discover the world was inherent in him, he changed his career path again in 1962 and began studying mathematics, physics, and astronomy – first in Karlsruhe, then in Heidelberg, where he graduated in 1967 with a degree in physics. He completed his PhD in nuclear physics there in 1969.

From 1969 to 1994, Josef Solf worked as one of the first scientific employees at the newly founded Max Planck Institute for Astronomy in Heidelberg, dedicating himself to the development of astronomical instruments and the study of star development.

He played a crucial role in establishing the institute's new observatory at Calar Alto in southern Spain. His focus soon turned to the development of spectroscopic instrumentation for the new telescopes. He gained knowledge during research stays at the Lick Observatory in California in 1971 and 1974, among others. A significant achievement was the Coudé spectrograph for the 2.2-meter telescope, a vertical setup through the entire dome building, which relied on a single mirror outside the telescope and undoubtedly represents one of the most powerful instruments of its kind. As a similar device promised no greater efficiency for the 3.5-meter telescope, interest there focused on a large Cassegrain spectrograph. Together with the institute's co-director, Guido Münch, Josef Solf developed the TWIN spectrograph, which became one of the workhorses at this telescope for a long time. He also converted a standard Boller & Chivens spectrograph according to his own design into a unique "echelle" spectrograph, which allowed imaging the entire spectral range from UV to near-infrared with a single exposure.

The commissioning and initial use of these devices made Josef Solf an observing astronomer. Initially, he observed late M-stars and Mira variables. His long-slit, high-spectral-resolution images of the prototypical massive star S106, together with Uri Carsenty, first revealed the blue and red shifts of the gas in its opposing extended shells, convincingly demonstrating the bipolar structure of these objects. This was followed by studies of bipolar outflows and jets from evolved stars such as R Aqr and the nova HR Delphini, which he also made the subject of his habilitation thesis in 1983, as well as work on bipolar planetary nebulae with his doctoral student Luis Felipe Miranda. He then turned to detailed spectroscopic studies of bipolar outflows and Herbig-Haro jets from young stars and their bow shocks together with Karl-Heinz Böhm. The method of spectro-astrometry that he developed to study these jets near the source was and is so successful that it was sometimes called "Solf's method" by some. In 1990, the University of Heidelberg appointed Josef Solf as a professor.

When Josef Solf received a call to a professorship in astronomy at the Friedrich Schiller University of Jena in 1994, combined with the position of director of the Thuringian State Observatory in Tautenburg, he returned to Jena, which he had left as a student in 1953. As a member of the Faculty of Physics and Astronomy, he was involved in teaching and scientific training of students until his retirement in 1999. As director of the Thuringian State Observatory Tautenburg, he contributed to the expansion of the institute and the modernization of the 2-meter Alfred Jensch telescope and its instrumentation. The construction of a new research building provided much-needed space for workrooms for scientists and administration. Laboratory space was also created for the electronics lab, as well as climate-controlled rooms for archiving the extensive collection of photographic plates of the Thuringian State Observatory and for their digital processing. An important concern for Josef Solf was the modernization of the 2-meter Alfred Jensch telescope, the largest optical telescope on German soil, which, through the renewal of its drives, enabled digital control. He designed the conversion of the high-resolution Coudé spectrograph into a Coudé echelle spectrograph, with vastly increased wavelength coverage, and conceived a low-resolution spectrograph for the Nasmyth focus of the telescope. With the active support of his former institute, the Max Planck Institute for Astronomy in Heidelberg, all focus stations received powerful CCD cameras as detectors.

After his retirement, Josef Solf remained active in the Catholic church choir in Jena. For many years, he was involved in the hospice association, accompanying numerous people in their darkest hours. He had three sons with his beloved wife Gisela, who passed away in 2017.

The Thuringian State Observatory has not only lost its former director and an outstanding scientist with Josef Solf but also a modest, energetic, and highly esteemed colleague. It will preserve his memory with honor.

Container laboratory weighing 5 tons floats to its destination

31.01.2024

The container for the future TauSol solar laboratory at the Thuringian State Observatory has been placed on a special foundation.

On Wednesday morning, January 31, 2024, at 8:30 a.m. the time had come. After the foundation for the new Solar LaboratoryOn Wednesday morning, January 31, 2024, at 8:30 a.m. the time had come. After the foundation for the new TauSol solar laboratory (see also news from ) was completed before Christmas, the weather and then the observatory's schedule did not play along at the beginning of the year. But this week the clayey ground had dried out and the weather was stable, so that the heavy mobile crane from Dorndorf was able to arrive. As the distance to the foundation was initially too great, the 12 m long and 5 ton container had to be parked once so that the truck-mounted crane could then lift the container onto the foundation from a position closer to the foundation on the second attempt. Accompanied and guided by the observatory's technical team, the container finally touched down in the specified position with almost millimeter precision - precision landing! Now the interior work and the installation of the dome above the container can begin. But first the container will get a new coat of paint - if the weather cooperates again. "TauSol solar laboratory was completed before Christmas, the weather and then the observatory's schedule did not play along at the beginning of the year. But this week the clayey ground had dried out and the weather was stable, so that the heavy mobile crane from Dorndorf was able to arrive. As the distance to the foundation was initially too great, the 12 m long and 5 ton container had to be parked once so that the truck-mounted crane could then lift the container onto the foundation from a position closer to the foundation on the second attempt. Accompanied and guided by the observatory's technical team, the container finally touched down in the specified position with almost millimeter precision - precision landing! Now the interior work and the installation of the dome above the container can begin. But first the container will get a new coat of paint - if the weather cooperates again.

A nebula beating at the rhythm of its newborn star

26.11.2023

An international team of astronomers lead by Prof. Roberto K. Saito of the Universidade Federal de Santa Catarina in Florianópolis, Brasil, reports the discovery of a unique object in our Galaxy. This object is located in the Scorpio constellation, close to the center of the Milky Way. It is observed as a peculiar combination of a variable star surrounded by a nebula that is also changing brightness. This discovery has been published on 2023 November 14 in The Astrophysical Journal Letters.

The discovery is made thanks to the VVV survey, that systematically mapped the Milky Way plane in the infrared with the VISTA telescope at ESO Paranal Observatory in Chile. The deep images accumulated along more than 12 years allow searching and monitor stars that change brightness with time. Tens of thousands of variable stars were discovered, that are classified according to their light curves. However, occasionally some object appears that cannot be easily explained because they do not belong to any of the known classes.

The VVV survey found a dozen such unidentified objects, that are called WIT, for “What Is This?”, and that represent very rare astrophysical phenomena. Such is the case of WIT-12, that was discovered in the infrared images using a simple technique that is generally applied to search for supernova light echoes. This technique consists of making color images using different observation epochs in the same filter. In this case the search was made using the images obtained in years 2010, 2011 and 2012 revealed a nebula that changes color, suggesting an interesting kind of variability. The follow-up study of the region revealed a red star located in the center of the nebula that changes brightness with a period of about 4 years. Follow-up spectroscopic observations made with the 4-m telescope SOAR at Cerro Pachón in Chile revealed that this central source is a very young stellar object that periodically illuminates the nebula. But the mystery does not end there, because the study that took so many years also revealed that the nebula changes brightness, and that one part varies in synch with the star, while the other part varies out of synch. That is, when the central star gets brighter, that part of the nebula fades.

This is an unknown phenomenon that perplexes the observers, motivating its classification as a WIT object, although the VVV team proposes a couple of explanations. This could be a central variable star that produces a light echo that reflects in the back part of the surrounding nebula. As the nebula is so extended, the light from the near side arrives directly to us, that region brightens when the star is brighter. On the other hand, the light that reflects on the more distant region of the nebula takes some time to travel, so it arrives later when the star is dimming. This phenomenon known as a light echo has been observed before in a few explosive events like novae and supernovae, but not in variable stars like WIT-12. Another possible explanation is the presence of a warped circumstellar disk that blocks light to different parts of the nebula as the warp moves around the star. This might be described as an ​"anti-light house", that illuminates all directions except one, in rotation. The final solution demands more observations and a new search for these kinds of objects, using telescopes like the future Vera C. Rubin Observatory.

The figure shows on the left the central star and two regions of the nebula encircled. Schematic light curves are displayed on the right, with colors corresponding to those on the left. While one region (red circle) is in phase with the stellar variability, the other one (cyan circle) is out of phase.

Contact: Dr. Bringfried Stecklum

Delivery of the TauSoL laboratory container

15.11.2023

On November 15 the "40-foot container" (approx. 12m long) for the new Tautenburg solar laboratory TauSol was delivered to the Thuringian State Observatory by a special truck. Until the foundation is completed, on which the container will be placed together with the beam frame for a dome and the heliostat, the container is now standing at the edge of the LOFAR radio telescope, where the interior work will begin.

Images: TLS

A new optics lab at TLS

13.11.2023

Today the first optical tables were set up in the new optics laboratory at the Thuringian State Observatory.

(Image: TLS)

In order to meet the growing demand for the development of new optical instruments at the TLS, a new optics laboratory is being set up. To this end, a basement room in the observatory's main building has been renovated over the past few months and equipped with new ventilation and electrical installations. Today the time had come and the first 3 m x 1.2 m optics table was set up. As it was not possible to transport such a large single table weighing around 600 kg into the cellar, it was assembled from two smaller parts weighing "only" 300 kg. But this transport also required skill, prudence and above all muscle power, which was provided by 6 employees of a Jena removal company. The first items to be measured in the new laboratory are special liquid crystal retarders for the observatory's new solar laboratory.

Image of the partial lunar eclipse

02.11.2023

On Saturday evening, October 28. 2023, a partial lunar eclipse occured, that could be observed through some clouds in Thuringia.

 The photo taken by TLS is showing the eclipse at 22h22 CEST.

Thuringian astronomers confirm an unusual extrasolar planet

26.09.2023

Astronomers at the Thuringian State Observatory and the University of Turin have succeeded in extracting some of the secrets of an unusual extrasolar planet.

The extrasolar planet GJ 367 b is exceptional because it appears to be entirely made of iron. It orbits its central star in just 7.7 hours. Researchers were not only able to determine the planet's density but also discovered two more planets around the star during their observations. This discovery adds another piece to the puzzle of how planets form.

Download the full report here