SOFIA Data Center (SDC)

With the release of the first version of the SOFIA Technical and Operations Archive, a central repository for the technical documentation of the SOFIA telescope is now available. SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a joint project of NASA and the German Aerospace Center (DLR). The new archive, known as the Technology and Operations Archive (TOA), consolidates relevant information on the telescope’s technology and operations and is hosted by the SOFIA Data Center (SDC) at the University of Stuttgart. A key task of the SDC is to process the SOFIA astronomical data from the operational years 2010 through 2022 for scientific use and make it accessible via a Virtual Observatory (VO).

As early as the SDC's planning phase, it was intended to permanently preserve not only the astronomical data but also the telescope’s technical and operational information. The goal is to document the technical knowledge gained during development, manufacturing, integration, and operation for the long term and make it available for future projects.

“The exceptional performance of the SOFIA telescope is particularly evident in its inertial stabilization,” emphasizes Michael Hütwohl, SDC project manager and former Telescope Manager for the SOFIA telescope. “Even with the telescope door open, at an altitude of about 41,000 feet, and at a flight speed of more than 850 km/h, the telescope could be aligned with its target with the highest precision for several hours.” This accuracy is illustrated by the fact that a laser pointer attached to the telescope would have kept its light spot within the circumference of a penny at a distance of 16 kilometers.

In addition to its astronomical tasks—such as the further development of data reduction methods and the establishment of the scientific archive—the SDC was therefore tasked with setting up the Technology and Operations Archive. “This underscores the special significance of the SOFIA telescope as Germany’s contribution to the joint SOFIA project with NASA,” said Hütwohl. Development, construction, and integration were carried out by a German consortium of companies led by MT Mechatronics GmbH (now OHB Digital Connect GmbH) and Kayser-Threde GmbH (now OHB System AG). The German SOFIA Institute at the University of Stuttgart was responsible for operations and continuous performance optimization.

The documentation follows the telescope’s Hardware Breakdown Structure (HBS). Each assembly is assigned a four-digit, hierarchical code; for example, HBS 1000 for the optical system and HBS 1100 for the primary mirror. This allows documents to be quickly and unambiguously assigned to and located within the various subsystems. During the active project phase, all documents were managed under version control in the Windchill document management system, ensuring that repairs, modifications, and further developments can be traced at any time. The final version of the documentation was subsequently transferred to the TOA.

The first version of the TOA, now available, primarily contains the telescope’s technical documentation. It is based on the so-called Acceptance Data Package (ADP), which consisted of approximately 150 file folders at the time of its handover to the DLR. The documents, which were originally available only in paper form, have been digitized, organized, and archived.

The archive will be continuously expanded in the coming years. Among other things, plans call for the inclusion of the complete maintenance documentation for the SOFIA telescope from the NASA Aircraft Maintenance Information System (NAMIS), which provides a detailed, chronological record of all maintenance, repairs, and modifications. In addition, further CAD models and simulation data are to be integrated. The finite element model of the SOFIA telescope is already available in the archive.

The Technology and Operations Archive is stored in the University of Stuttgart’s data repository (DaRUS). The platform, which is based on the open-source software Dataverse, enables the structured management of large datasets. Extensive metadata ensures that datasets and files can be efficiently searched and quickly located using filters. This structure also makes it easier for users outside the field to access the content and supports the transfer of knowledge to future projects with similar technical challenges. The University of Stuttgart’s Research Data Management team provided intensive support during the development of the archive.

University of Stuttgart employees can log in to DaRUS using their account. External users must obtain prior authorization, which can be requested through the SDC at DLR. The data verses and datasets available in DaRUS can be viewed without logging in. However, access to the files they contain is only possible with the appropriate authorization.

Detailed instructions on how to use the archive are provided in the document “Using the SOFIA Technology and Operations Archive.”

Contact:

Dipl.-Ing. Michael Hütwohl
Project Manager, SOFIA Data Center
Phone: +49 711 685 69636
Email: michael.huetwohl@irs.uni-stuttgart.de

Dr.-Ing. Benjamin Greiner
Research Associate, SOFIA Data Center
Phone: +49 711 685 69624
Email: benjamin.greiner@irs.uni-stuttgart.de

Further links related to this news:

• SOFIA Technology and Operations Archive (TOA) in the University of Stuttgart Data Repository (DaRUS)
• User Guide for the Technology and Operations Archive (TOA)
• SOFIA Data Center (SDC) at the University of Stuttgart
• SOFIA: Data goldmine for astronomical research, News of the University of Stuttgart, September 12, 2024

Further SOFIA links:

• SOFIA data collection at the IPAC Infrared Science Archive
• NASA SOFIA mission page
• SOFIA Missionsseite der DLR Raumfahrtagentur (German)

The SOFIA Data Center (SDC) is funded by the DLR Space Agency under grant number FKZ 50OK2404.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a joint project of the German Aerospace Center (DLR; funding codes 50OK0901, 50OK1301, 50OK1701, and 50OK2002) and the National Aeronautics and Space Administration (NASA). It was carried out at the instigation of the DLR with funds from the Federal Ministry for Economic Affairs and Climate Protection (BMWE) on the basis of a resolution by the German Bundestag and with funds from the state of Baden-Württemberg and the University of Stuttgart. On the German side, SOFIA activities were coordinated by the German Space Agency at DLR and carried out by the German SOFIA Institute (DSI) at the University of Stuttgart, and on the American side by NASA and the Universities Space Research Association (USRA). The development of the German instruments was financed with funds from the Max Planck Society (MPG), the German Research Foundation (DFG), and the DLR.

Aerospace research at the University of Stuttgart
Aerospace studies in Stuttgart form a unique interdisciplinary think tank for key technologies in space and on Earth. Researchers at the University of Stuttgart bring together expertise from the fields of climate and energy research, communications technology, propulsion technology, and AI-assisted flight. A central focus is the exploration of sustainable technological solutions aimed at minimizing the environmental impact of aerospace. Research is conducted in an interdisciplinary manner and in close collaboration with regional and international partners from academia and industry, for example within the framework of the Collaborative Research Centers ATLAS (SFB 1667) and SynTrac (SFB-TRR 364). As a partner of THE Aerospace LÄND, the University of Stuttgart contributes to the implementation of Baden-Württemberg’s state strategy to shape aerospace in a sustainable, digital, and collaborative manner by 2050. The University offers its students a solid engineering and application-oriented education. In promoting young talent, it cooperates with the “Future Initiative for Young Talent in Aerospace,” an initiative of the state of Baden-Württemberg dedicated to strengthening the promotion of young talent in STEM fields.

The new version of the SOFIA data reduction pipeline, Redux 1.5, is now available. It includes a wide range of updates. Highlights are improved flux calibration from FIFI-LS, new transmission spectra for enhanced telluric correction - derived using an optimized version of the ATRAN software (ATRAN_SDC) - and updated documentation. For more information, visit this link.

The SOFIA Data Center just released a complete set of atmospheric transmission models calculated for altitudes between 35.000 and 45.000 ft (~ 11 - 14 km) and precipitable water vapor levels of 1 to 50 µm. This dataset is used by the REDUX data processing pipeline to correct FIFI-LS astronomical observations for the influence of the residual atmosphere above the flying observatory SOFIA.

FIFI-LS was SOFIA's high sensitivity imaging spectrometer, which conducted astrophysical research at far-infrared wavelengths, contributing to our understanding of star formation and the interstellar medium.

The published transmission models cover the wavelength range between 40 and 300 µm and were calculated by SDC-ATRAN, a modified version of Steve Lord's well known ATRAN program for the purposes of SOFIA. The models are stored as FITS binary tables, which is a well-established standard format in astronomy. Online storage of these files at the University of Stuttgart enables the REDUX software to automatically download specifically needed files when processing observations without the need to transfer the entire dataset.

The dataset is publicly available via DaRUS, the data repository of the University of Stuttgart: https://darus.uni-stuttgart.de/dataverse/irs-sofia-ad

SOFIA Data Center releases new software version: SOFIA Redux 1.4

The SOFIA Data Center (SDC) at the University of Stuttgart has released version 1.4 of the SOFIA Redux data reduction software. With this release, the SDC officially takes over the further development of the software, which was developed and maintained by the SOFIA Science Mission Operations Center (SMO) at NASA Ames Research Center in Mountain View, California, until its closure in August 2023.

SOFIA Redux (sofia_redux) provides powerful data reduction pipelines for the following instruments of the Stratospheric Observatory for Infrared Astronomy (SOFIA):

• EXES – Echelon X (cross) Echelle Spectrograph
  High-resolution spectrometer (4,5–28,3 µm)
• FIFI-LS – Field Imaging Far-Infrared Line Spectrometer
  Integral field spectrometer (51–200 µm)
• FLITECAM – First Light Infrared Test Experiment CAMera
  Imager with filters and grisms (1,0–5,5 µm)
• FORCAST – Faint Object infraRed CAmera for the SOFIA Telescope
  Imager with filters and grisms (5–40 µm)
• HAWC+ – High-Resolution Airborne Wideband Camera
  Imager with filters and grisms (50–240 µm)

This new software version is primarily a technical upgrade of the previous version 1.3.3 and fixes issues that arose due to further developments of the underlying libraries. In addition, SOFIA Redux 1.4 contains improvements for the FIFI-LS package in terms of calibration and data quality. All new features are described in detail in the accompanying documentation, which is available free of charge on GitHub together with the software: https://github.com/SOFIA-Data-Center/sofia_redux

The SOFIA Data Center (SDC) is also planning further improvements for the EXES, FIFI-LS, FORCAST, and HAWC+ instruments. As in the past, GREAT data will continue to be processed at the University of Cologne. Due to the small volume of FLITECAM data resulting from the few missions flown, no additional or improved processing procedures are currently planned.
The SDC expressly welcomes collaboration with external developers. Contributions can be submitted in the form of pull requests, provided they comply with current open source standards.

With the release of the SOFIA Redux 1.4 software version, the SOFIA Data Center is underscoring its role as a central competence center for the sustainable use of SOFIA data. The SDC is currently preparing a comprehensive reprocessing of the data sets. Among other things, improved pointing information from the guide cameras, optimized correction of telluric water vapor, and further methodological improvements are planned. The processed data will be made available via a VO-compatible online archive. The Virtual Observatory (VO) is an international standard that digitally networks astronomical data from different observatories and makes it accessible via uniform interfaces. At the end of the SDC's active phase in mid-2029, the archive is scheduled to be transferred to the German Center for Astrophysics (DZA) in Görlitz.

Contact:
Dr. Bernhard Schulz
Project Scientist, SOFIA Data Center
Phone: +49 174 532 6516
E-Mail: bernhard.schulz@irs.uni-stuttgart.de

Dr. Benjamin Greiner
Research Associate, SOFIA Data Center
Phone: +49 711 685 69624
E-Mail: benjamin.greiner@irs.uni-stuttgart.de

Further links with respect to the news:

• SOFIA Data Center (SDC) at the University of Stuttgart
• SOFIA: Data goldmine for astronomical research, news of the University of Stuttgart, 12. September 2024

Further SOFIA Links:

• SOFIA data center at IPAC Infrared Science Archive
• NASA SOFIA mission page
• SOFIA mission page at DLR (German Space Agency)  (in German) 

The SOFIA Data Center (SDC) is funded by the German Aerospace Center (DLR) under grant number FKZ 50OK2404.

SOFIA, the Stratospheric Observatory for Infrared Astronomy, was a joint project of the German Aerospace Center (DLR; funding codes 50OK0901, 50OK1301, 50OK1701, and 50OK2002) and the National Aeronautics and Space Administration (NASA). It was carried out at the instigation of the DLR with funds from the Federal Ministry for Economic Affairs and Climate Protection (BMWE) on the basis of a resolution by the German Bundestag and with funds from the state of Baden-Württemberg and the University of Stuttgart. On the German side, SOFIA activities were coordinated by the German Space Agency at DLR and carried out by the German SOFIA Institute (DSI) at the University of Stuttgart, and on the American side by NASA and the Universities Space Research Association (USRA). The development of the German instruments was financed with funds from the Max Planck Society (MPG), the German Research Foundation (DFG), and the DLR

Aerospace research at the University of Stuttgart
Stuttgart's aerospace studies are a unique interdisciplinary think tank for key technologies in space and on Earth. Researchers at the University of Stuttgart combine expertise in the fields of climate and energy research, communication technology, propulsion technology, and AI-based flying. A central focus is the research of sustainable technological solutions that aim to minimize the ecological impact of aerospace. Research is conducted on an interdisciplinary basis and in close dialogue with regional and international partners from science and industry, for example within the framework of the ATLAS (SFB 1667) and SynTrac (SFB-TRR 364) collaborative research centers. As a partner of THE Aerospace LÄND, the University of Stuttgart contributes to the implementation of Baden-Württemberg's state strategy to make aerospace sustainable, digital, and cooperative by 2050. The university offers its students a sound engineering and application-oriented education. In promoting young talent, it cooperates with the “Zukunftsoffensive Luft- und Raumfahrt-Nachwuchs” (Future Promotion Opportunities for Young Aerospace Talent), an initiative of the state of Baden-Württemberg that is committed to strengthening the promotion of young talent in the STEM subjects.

Aaron Bryant successfully completes dissertation

On Friday, January 23, 2026, our colleague and SDC employee Aaron Bryant successfully defended his dissertation entitled “Observations of the Galactic Center Circumnuclear Disk with FIFI-LS”. The astronomical data that served as the basis for this work was obtained on numerous flights with the SOFIA observatory in the northern and southern hemisphere.

Insight into the research

The galactic center of our Milky Way is the scene of diverse astrophysical processes and still raises pressing questions. These include, in particular, the formation history of a cluster of massive young stars surrounding the supermassive black hole Sgr A*.

Mr. Bryant used the spectroscopic capabilities of the FIFI-LS instrument to map the inner parsecs of the galactic center in several far-infrared spectral lines. The physical properties of the region derived from this data make it clear that gas density alone is not sufficient to withstand the enormous tidal forces of Sgr A*. This suggests that additional processes must have been at work if the star cluster did indeed form in this region.

Beyond the dissertation

In addition to the scientific analyses, Mr. Bryant's work includes a current overview of the galactic center and documentation of his activities during the flight operations of FIFI-LS aboard SOFIA.

We are delighted that Mr. Bryant is continuing his work at the SDC. He is currently focusing on the further development of the FIFI-LS and EXES pipelines in preparation for a new reduction of the SOFIA science archive.

The whole team says: Congratulations, Dr. Bryant!

SOFIA made it onto the cover of the German Physics Journal

The January 2026 issue of the Physics Journal of the German Physical Society (DPG) features an extensive article by Prof. Dr. Alfred Krabbe on the SOFIA project. Alfred Krabbe was director of the German SOFIA Institute (DSI) at the University of Stuttgart and played a key role in shaping Germany's contribution to the SOFIA project. The article is available for download in German only at:
https://pro-physik.de/zeitschriften/physik-journal/2026-1/