{"f016e9218cc56b86093fde125c2ce1d9sofiabgreiner":{"DOI":"10.5281/ZENODO.17980055","ISBN":"","ISSN":"","URL":"https://zenodo.org/doi/10.5281/zenodo.17980055","abstract":"","annote":"","author":[{"family":"Greiner","given":"Benjamin"},{"family":"Knieling","given":"Bastian"},{"family":"Bryant","given":"Aaron"},{"family":"Früh","given":"Jonas"},{"family":"Fischer","given":"Nadine"},{"family":"Valek","given":"Rainer"}],"citation-label":"https://doi.org/10.5281/zenodo.17980055","collection-editor":[],"collection-title":"","container-author":[],"container-title":"","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2025"]],"literal":"2025"},"event-place":"","id":"f016e9218cc56b86093fde125c2ce1d9sofiabgreiner","interhash":"72ff4a74ca0faf1713de6a9f4897d238","intrahash":"f016e9218cc56b86093fde125c2ce1d9","issue":"","issued":{"date-parts":[["2025"]],"literal":"2025"},"keyword":"myown sofia","misc":{"copyright":"BSD 3-Clause \"New\" or \"Revised\" License","doi":"10.5281/ZENODO.17980055"},"note":"","number":"","page":"","page-first":"","publisher":"Zenodo","publisher-place":"","status":"","title":"SOFIA-Data-Center/sofia_redux","type":"article","username":"sofiabgreiner","version":"","volume":""},"9a6086eb0b83688b27e3016b60b0f3e9asteroidguy":{"DOI":"10.3847/PSJ/ad3819","ISBN":"","ISSN":"","URL":"https://doi.org/10.3847/PSJ/ad3819","abstract":"","annote":"","author":[{"family":"Knieling","given":"Bastian"},{"family":"Schindler","given":"Karsten"},{"family":"Sickafoose","given":"Amanda A."},{"family":"Person","given":"Michael J."},{"family":"Levine","given":"Stephen E."},{"family":"Krabbe","given":"Alfred"}],"citation-label":"knieling2024stellar","collection-editor":[],"collection-title":"","container-author":[],"container-title":"The Planetary Science Journal","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2024","04","01"]],"literal":"2024"},"event-place":"","id":"9a6086eb0b83688b27e3016b60b0f3e9asteroidguy","interhash":"8a31ef0ec16c1fb74451a1f85d2cc0d6","intrahash":"9a6086eb0b83688b27e3016b60b0f3e9","issue":"","issued":{"date-parts":[["2024","04","01"]],"literal":"2024"},"keyword":"SOFIA imported myown","misc":{"doi":"10.3847/PSJ/ad3819"},"note":"","number":"","page":"","page-first":"","publisher":"","publisher-place":"","status":"","title":"Stellar Occultations in the Era of Data Mining and Modern Regression Models: Using Gaussian Processes to Analyze Light Curves and Improve Predictions","type":"article-journal","username":"asteroidguy","version":"","volume":""},"865ef5b00fbdd3c82c9750ce6653a805asteroidguy":{"DOI":"","ISBN":"","ISSN":"","URL":"","abstract":"We present results obtained from a stellar occultation by the classical Kuiper belt object (174567) Varda on 10 September 2018. Varda is a known binary system and among the largest TNOs known today, but has not been studied during an occultation before. Among our collaborators, 24 stations were able to acquire data at the time of the event, of which 15 obtained a clear detection, making this the best-sampled occultation of a TNO to date. As potential stellar duplicity could cause a significant shift of the ground path, we studied the target star in advance through speckle imaging with 'Alopeke at Gemini North. The reconstructed shape is an ellipsoid, which supports Varda's status as a dwarf planet candidate. Albeit slightly smaller, the calculated size is in agreement with the radiometric diameter based on Herschel/PACS FIR measurements. Post-event analysis of the dataset obtained at DCT revealed a faint, unresolved companion or background star very close to the target, which was well under the detection limit of our speckle imager data, but had practically no effect on the predicted path. No atmosphere has been detected. The occultation helped to constrain size and albedo, which in turn helps to better constrain Varda's density....","annote":"","author":[{"family":"Schindler","given":"K."},{"family":"Bosh","given":"A. S."},{"family":"Levine","given":"S. E."},{"family":"Person","given":"M. J."},{"family":"Wolf","given":"J."},{"family":"Zuluaga","given":"C."},{"family":"Krabbe","given":"A."}],"citation-label":"schindler2019results","collection-editor":[],"collection-title":"","container-author":[],"container-title":"AGU Fall Meeting Abstracts","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2019","12"]],"literal":"2019"},"event-place":"","id":"865ef5b00fbdd3c82c9750ce6653a805asteroidguy","interhash":"f835d4bfeb603bb750b040984548f31b","intrahash":"865ef5b00fbdd3c82c9750ce6653a805","issue":"","issued":{"date-parts":[["2019","12"]],"literal":"2019"},"keyword":"ATUS SOFIA astronomy imported myown","misc":{"bibcode":"2019AGUFM.P42C..08S"},"note":"","number":"","page":"","page-first":"","publisher":"","publisher-place":"","status":"","title":"Results from a stellar occultation by KBO Varda","type":"article","username":"asteroidguy","version":"","volume":""},"aa7d67a7e50ac7085306cee751c6e677sofiabgreiner":{"DOI":"10.1117/12.3019062","ISBN":"","ISSN":"","URL":"https://doi.org/10.1117/12.3019062","abstract":"","annote":"","author":[{"family":"Greiner","given":"Benjamin"},{"family":"Hofmann","given":"Sonja"},{"family":"Wagner","given":"Jörg F."}],"citation-label":"10.1117/12.3019062","collection-editor":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"collection-title":"","container-author":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"container-title":"Ground-based and Airborne Telescopes X","documents":[],"edition":"","editor":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"event-date":{"date-parts":[["2024"]],"literal":"2024"},"event-place":"","id":"aa7d67a7e50ac7085306cee751c6e677sofiabgreiner","interhash":"37e3035ffd7a2f810fbd62a51093a1ad","intrahash":"aa7d67a7e50ac7085306cee751c6e677","issue":"","issued":{"date-parts":[["2024"]],"literal":"2024"},"keyword":"damping myown sofia vibration","misc":{"doi":"10.1117/12.3019062"},"note":"","number":"","page":"1309444","page-first":"1309444","publisher":"SPIE","publisher-place":"","status":"","title":"SOFIA performance improvements through active mass damping","type":"paper-conference","username":"sofiabgreiner","version":"","volume":"13094"},"aa7d67a7e50ac7085306cee751c6e677pas":{"DOI":"10.1117/12.3019062","ISBN":"","ISSN":"","URL":"https://doi.org/10.1117/12.3019062","abstract":"","annote":"","author":[{"family":"Greiner","given":"Benjamin"},{"family":"Hofmann","given":"Sonja"},{"family":"Wagner","given":"Jörg F."}],"citation-label":"10.1117/12.3019062","collection-editor":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"collection-title":"","container-author":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"container-title":"Ground-based and Airborne Telescopes X","documents":[],"edition":"","editor":[{"family":"Marshall","given":"Heather K."},{"family":"Spyromilio","given":"Jason"},{"family":"Usuda","given":"Tomonori"}],"event-date":{"date-parts":[["2024"]],"literal":"2024"},"event-place":"","id":"aa7d67a7e50ac7085306cee751c6e677pas","interhash":"37e3035ffd7a2f810fbd62a51093a1ad","intrahash":"aa7d67a7e50ac7085306cee751c6e677","issue":"","issued":{"date-parts":[["2024"]],"literal":"2024"},"keyword":"pas myown damping sofia myownsend:unibiblio vibration","misc":{"doi":"10.1117/12.3019062"},"note":"","number":"","page":"1309444","page-first":"1309444","publisher":"SPIE","publisher-place":"","status":"","title":"SOFIA performance improvements through active mass damping","type":"paper-conference","username":"pas","version":"","volume":"13094"},"d25e0115e6a549132587b910b45f9d6dsofiabgreiner":{"DOI":"","ISBN":"978-3-8439-5435-8","ISSN":"","URL":"","abstract":"During the design and development of mechanical systems, mathematical models\r\nare a common tool to analyze, predict and characterize the behavior\r\nof a structure. For a model to accurately describe the \r\nphysical behavior of a system, the model type and structure must be suitable \r\nfor the analysis type. In structural dynamics, simulations employing finite \r\nelement models of lightweight structures are used to assess the vibration \r\nresponse due to internal and external loads. With appropriately chosen \r\napproximations for the model, the simulation results depend on the values of \r\nmodel parameters. The identification of such parameters, the \r\ndetermination of their role and quantitative contribution towards the behavior \r\nof a model, is an important task during the process of modeling. Measurement\r\ndata from experiments are used as reference values to tune and validate the \r\nresults from model analyses.\r\n\r\nComplex structures with a significant number of sub-components tend to require \r\ncomplex models in order to reflect their physical behavior accurately. This \r\nincreases the number of parameters, which poses difficulties during the \r\nidentification process due to overlaps in parameter effects. Furthermore the\r\nsize of associated optimization problems increases prohibitively.\r\n\r\nThis thesis presents a multi-stage approach for identifying model parameters of \r\ncomplex lightweight structures. Instead of identifying model parameters for a \r\nfully integrated structure at once, sub-assemblies and individual parts are \r\nanalyzed separately. Model parameters identified in sub-assembly stages are \r\nthen incorporated into an assembled model. As measurement data and identified\r\nparameters are associated with uncertainty distributions, errors in the\r\nidentification of parameters of upstream stages propagate into higher assembly\r\nmodels. Accordingly, such propagating errors should be minimized in early\r\nstages. Additionally, this effect has to be taken into account during the\r\nrefinement of existing parameter in later stages and for the assessment\r\nof model accuracy at higher assembly levels.\r\n\r\n\r\nThe staged identification has been applied to two distinct structures: First,\r\nin order to validate the principles of staged identification,\r\na cantilevered truss-like space frame beam structure has been modeled and \r\nmeasured in an laboratory setup. Data from previous studies pertaining the \r\nstructure as well as new measurements from experimental modal analysis have been \r\nused to identify a finite element model. The structure was divided into a cell \r\nand a short beam configuration in order to simulate sub-assemblies for the staged\r\napproach.\r\n\r\nA second, more complex, structure which motivated the work on this thesis is\r\nthe SOFIA Telescope Assembly. A legacy finite element model, constructed\r\nduring the design and integration phase of the telescope, exists but was\r\nmodeled with a focus on the qualification regarding flight-worthiness\r\nand the fulfillment of specifications using conservative\r\nparameter values. The model has been updated\r\nthrough staged parameter identification in order to be suitable for simulations\r\nunder the environment of operational conditions with a focus on\r\ndynamic characteristics affecting the optical path. A multitude of data sources\r\nfrom the project documentation archive as well as new measurements with\r\ntest benches and flight hardware have been used to update single parts\r\nand major assemblies, such as the Primary Mirror Assembly and\r\nSecondary Mirror Mechanism of the telescope. Comparisons of modal analyses\r\nusing the updated integrated Telescope Assembly model with ground-based\r\nand in-flight modal surveys show the improvement of accuracy of the model.\r\nTogether with the reorganization of model structure and handling through\r\nprogram scripts, the new model is suitable for further analyses in support\r\nof improving the performance of the observatory through enhanced control systems\r\nand the reduction of image jitter.","annote":"","author":[{"family":"Greiner","given":"Benjamin"}],"citation-label":"greiner2024multistagemodelid","collection-editor":[],"collection-title":"","container-author":[],"container-title":"","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2024"]],"literal":"2024"},"event-place":"","id":"d25e0115e6a549132587b910b45f9d6dsofiabgreiner","interhash":"3d5d2387457cc624a0f97b015dda2495","intrahash":"d25e0115e6a549132587b910b45f9d6d","issue":"","issued":{"date-parts":[["2024"]],"literal":"2024"},"keyword":"control myown sofia","misc":{"isbn":"978-3-8439-5435-8","language":"English"},"note":"","number":"","page":"","page-first":"","publisher":"Dr. Hut Verlag","publisher-place":"","status":"","title":"Multi Stage Model Identification of Complex Lightweight Structures","type":"thesis","username":"sofiabgreiner","version":"","volume":""},"bf9cad4eab85086a41d9a0ad7fe6e494sofiabgreiner":{"DOI":"10.1002/pamm.201710120","ISBN":"","ISSN":"1617-7061","URL":"","abstract":"","annote":"","author":[{"family":"Greiner","given":"Benjamin"},{"family":"Wagner","given":"Jörg F."}],"citation-label":"greiner2017multistage","collection-editor":[],"collection-title":"","container-author":[],"container-title":"Proceedings in Applied Mathematics and Mechanics, PAMM","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2017"]],"literal":"2017"},"event-place":"","id":"bf9cad4eab85086a41d9a0ad7fe6e494sofiabgreiner","interhash":"b62e71c37ad468a8677462c631fe4c1f","intrahash":"bf9cad4eab85086a41d9a0ad7fe6e494","issue":"1","issued":{"date-parts":[["2017"]],"literal":"2017"},"keyword":"myown sofia","misc":{"issn":"1617-7061","doi":"10.1002/pamm.201710120"},"note":"","number":"1","number-of-pages":"1","page":"301--302","page-first":"301","publisher":"","publisher-place":"","status":"","title":"Multi-stage parameter identification of structural models from experimental data of varying assembly levels","type":"paper-conference","username":"sofiabgreiner","version":"","volume":"17"},"922edcb2bea36a48f89ae124fdfbda53sofiabgreiner":{"DOI":"10.1117/12.2561373","ISBN":"","ISSN":"","URL":"https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11445/2561373/Reactivation-of-the-active-mass-damping-system-for-SOFIA-to/10.1117/12.2561373.full?SSO=1","abstract":"The Stratospheric Observatory for Infrared Astronomy (SOFIA) employs an airborne telescope with a 2.7m primary mirror. The telescope structure is composed of carbon fibre with major parts of steel for the suspension and balancing components. It is exposed to harsh environmental conditions and subject to vibration excitation due to aircraft motions and turbulence from the airflow coming into the telescope cavity. To meet pointing requirements and improve image stability there are ongoing efforts on various components of the telescope system, one of which is the implementation of an Active Mass Damping (AMD) control system: Based on accelerometer signals, reaction mass actuators impose forces onto the support structure to dampen the vibration of optical components. The system has been designed, implemented and preliminary tested in the early years of SOFIA’s scientific operation, but concerns about the structural integrity of the primary mirror and new requirements regarding software qualification have prevented the activation and further development for several years. These concerns being addressed, we are now in the process of reactivating the AMD system on the support structure of the primary mirror. Recent ground tests and in-flight jitter measurements indicate that the damping system is very efficient at eliminating the excitation of targeted structural modes of the telescope structure at 40 to 80 Hz and the first bending modes of the primary mirror at 175 Hz, resulting in a significantly improved image quality. This paper presents the analysis of those measurements and discusses options for future development.","annote":"","author":[{"family":"Greiner","given":"Benjamin"},{"family":"Brewster","given":"Rick"},{"family":"Mrzyglod","given":"Anja"},{"family":"Wagner","given":"Jörg"}],"citation-label":"greinerreactivation","collection-editor":[],"collection-title":"","container-author":[],"container-title":"Ground-based and Airborne Telescopes VIII","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2020"]],"literal":"2020"},"event-place":"","id":"922edcb2bea36a48f89ae124fdfbda53sofiabgreiner","interhash":"ff4ae65361f948475e5629bf38f279c6","intrahash":"922edcb2bea36a48f89ae124fdfbda53","issue":"","issued":{"date-parts":[["2020"]],"literal":"2020"},"keyword":"AMD myown sofia","misc":{"doi":"10.1117/12.2561373"},"note":"","number":"","page":"114450W-","page-first":"114450","publisher":"International Society for Optics and Photonics","publisher-place":"","status":"","title":"Reactivation of the active mass damping system for SOFIA to improve image stability","type":"paper-conference","username":"sofiabgreiner","version":"","volume":"11445"},"6435b0b88b23a7423eb0ee3cab525df3sofiabgreiner":{"DOI":"10.1117/12.2232152","ISBN":"","ISSN":"","URL":"https://doi.org/10.1117/12.2232152","abstract":"The Stratospheric Observatory For Infrared Astronomy (SOFIA) reached its full operational capability in 2014 and takes off from the NASA Armstrong Flight Research Center to explore the universe about three times a week. Maximizing the program's scientific output naturally leaves very little flight time for implementation and test of improved soft- and hardware. Consequently, it is very important to have a comparable test environment and infrastructure to perform troubleshooting, verifications and improvements on ground without interfering with science missions. SOFIA's Secondary Mirror Mechanism is one of the most complex systems of the observatory. In 2012 a first simple laboratory mockup of the mechanism was built to perform basic controller tests in the lower frequency band of up to 50Hz. This was a first step to relocate required engineering tests from the active observatory into the laboratory. However, to test and include accurate filters and damping methods as well as to evaluate hardware modifications a more precise mockup is required that represents the system characteristics over a much larger frequency range. Therefore the mockup has been improved in several steps to a full test environment representing the system dynamics with high accuracy. This new ground equipment allows moving almost the entire secondary mirror test activities away from the observatory. As fast actuator in the optical path, the SMM also plays a major role in SOFIA's pointing stabilization concept. To increase the steering bandwidth, hardware changes are required that ultimately need to be evaluated using the telescope optics. One interesting concept presented in this contribution is the in- stallation of piezo stack actuators between the mirror and the chopping mechanism. First successful baseline tests are presented. An outlook is given about upcoming performance tests of the actively controlled piezo stage with local metrology and optical feedback. To minimize the impact on science time, the laboratory test setup will be expanded with an optical measurement system so that it can be used for the vast majority of testing.","annote":"","author":[{"family":"Lammen","given":"Yannick"},{"family":"Reinacher","given":"Andreas"},{"family":"Brewster","given":"Rick"},{"family":"Greiner","given":"Benjamin"},{"family":"Graf","given":"Friederike"},{"family":"Krabbe","given":"Alfred"}],"citation-label":"10.1117/12.2232152","collection-editor":[{"family":"Hall","given":"Helen J."},{"family":"Gilmozzi","given":"Roberto"},{"family":"Marshall","given":"Heather K."}],"collection-title":"","container-author":[{"family":"Hall","given":"Helen J."},{"family":"Gilmozzi","given":"Roberto"},{"family":"Marshall","given":"Heather K."}],"container-title":"Ground-based and Airborne Telescopes VI","documents":[],"edition":"","editor":[{"family":"Hall","given":"Helen J."},{"family":"Gilmozzi","given":"Roberto"},{"family":"Marshall","given":"Heather K."}],"event-date":{"date-parts":[["2016"]],"literal":"2016"},"event-place":"","id":"6435b0b88b23a7423eb0ee3cab525df3sofiabgreiner","interhash":"430047e3b74e21d7ab75a8db42b36168","intrahash":"6435b0b88b23a7423eb0ee3cab525df3","issue":"","issued":{"date-parts":[["2016"]],"literal":"2016"},"keyword":"SOFIA myown","misc":{"doi":"10.1117/12.2232152"},"note":"","number":"","page":"99064T","page-first":"99064","publisher":"SPIE","publisher-place":"","status":"","title":"A new test environment for the SOFIA secondary mirror assembly to reduce the required time for in-flight testing","type":"paper-conference","username":"sofiabgreiner","version":"","volume":"9906"},"af69be0375e4e7816ce75d9b1bb45b73sofiabgreiner":{"DOI":"","ISBN":"","ISSN":"","URL":"http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-50403","abstract":"","annote":"","author":[{"family":"Greiner","given":"Benjamin"}],"citation-label":"greiner2009Operationalmodal","collection-editor":[],"collection-title":"","container-author":[],"container-title":"","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2009"]],"literal":"2009"},"event-place":"","id":"af69be0375e4e7816ce75d9b1bb45b73sofiabgreiner","interhash":"4c143b1f22552eee07a6667b70055287","intrahash":"af69be0375e4e7816ce75d9b1bb45b73","issue":"","issued":{"date-parts":[["2009"]],"literal":"2009"},"keyword":"Astronomie Modalanalyse SOFIA Schwingung Strukturdynamik Systemidentifikation myown","misc":{"note2":"Online publiziert 2010","language":"Englisch"},"note":"Online-Ressource","number":"","page":"","page-first":"","publisher":"Universitätsbibliothek der Universität Stuttgart","publisher-place":"","status":"","title":"Operational modal analysis and its application for SOFIA telescope assembly vibration measurements","type":"thesis","username":"sofiabgreiner","version":"","volume":""},"3176b0c6bac24bf8d47efc2014b2a05dasteroidguy":{"DOI":"","ISBN":"","ISSN":"","URL":"https://ui.adsabs.harvard.edu/abs/2018DPS....5041610P/abstract","abstract":"","annote":"","author":[{"family":"Person","given":"Michael J."},{"family":"Schindler","given":"Karsten"},{"family":"Bosh","given":"Amanda S."},{"family":"Wolf","given":"Juergen"},{"family":"Levine","given":"Stephen E."},{"family":"Zuluaga","given":"Carlos A."},{"family":"Pfueller","given":"Enrico"},{"family":"Caton","given":"Daniel"},{"family":"Patton","given":"Alexander"},{"family":"Pasachoff","given":"Jay"},{"family":"Oswalt","given":"Terry"},{"family":"von Hippel","given":"Ted"},{"family":"Brothers","given":"Timothy"},{"family":"SOFIA Operations Team","given":""},{"family":"Lincoln Labs Firepond Observations Team","given":""},{"family":"Triton Occultation Observation Team","given":""}],"citation-label":"Person2018","collection-editor":[],"collection-title":"","container-author":[],"container-title":"AAS/Division for Planetary Sciences Meeting Abstracts","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2018","oct"]],"literal":"2018"},"event-place":"","id":"3176b0c6bac24bf8d47efc2014b2a05dasteroidguy","interhash":"549ebda5e041708d650f1025f497a016","intrahash":"3176b0c6bac24bf8d47efc2014b2a05d","issue":"","issued":{"date-parts":[["2018","oct"]],"literal":"2018"},"keyword":"SOFIA astronomy myown","note":"","number":"","page":"416.10","page-first":"416","publisher":"","publisher-place":"","status":"","title":"Airborne and Ground Observations of the Stellar Occultation by Triton on 5 October 2017","type":"article-journal","username":"asteroidguy","version":"","volume":"50"},"0d1867933896c048069ff6b741cb0bfdasteroidguy":{"DOI":"10.1117/12.2313663","ISBN":"","ISSN":"","URL":"https://www.dsi.uni-stuttgart.de/institut/mitarbeiter/schindler/Pfueller_et_al._2018.pdf","abstract":"The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a heavily modified Boeing 747SP aircraft, accommodating a 2.7 meter infrared telescope. This airborne observation platform operates at flight altitudes of up to 13.7 km (45,000 ft) and therefore allows a nearly unobstructed view of the visible and infrared universe at wavelengths between 0.3 µm and 1600 µm. The Focal Plane Imager (FPI+) is SOFIA’s main tracking camera. It uses a commercial, off-the-shelf camera with a thermoelectrically cooled EM-CCD. The back-illuminated sensor has a peak quantum efficiency greater than 95% at 550 nm and the dark current is as low as 0.01 e-/pix/sec. Since 2015, the FPI+ has been available to the community as a Facility Science Instrument, and can be used to observe stellar occultations by solar system objects such as dwarf planets, moons, asteroids, and comets, and transits of extra-solar planets. To date, SOFIA has conducted multi-channel observations of occultations, e.g. the occultation by Pluto in June of 2015 or the occultation by Triton in October 2017, using three instruments, HIPO and FLITECAM at the main instrument flange of the telescope, and the FPI+. This multi-wavelength sampling is important for enabling discrimination of particle sizes and constituents of hazes in the atmosphere of bodies such as Pluto and Triton, and the coma material of comets. Multi-wavelength observations also serve to allow us to place constraints on the chemical compositions of these formations. After the retirement of the two other instruments, the FPI+ is now SOFIA’s only remaining observing tool for occultations. In order to preserve some of the multi-color observing capability of the platform, we here discuss the addition of a second spectral channel to the FPI+. In a first upgrade step, a beamsplitter will split the incoming light and send it to two EMCCD cameras, one working in the ”blue”, e.g. SLOAN g’ band, and the other working in the ”red”, e.g. SLOAN i’ or z’ band. In a second upgrade step, the ”red” channel could be equipped with a NIR camera in order to provide a wider wavelength separation of the two bands. This will however require a modified dichroic coating on the tertiary (Nasmyth) mirror of the SOFIA telescope. This paper presents a preliminary design study of the opto-mechanical configuration of the dual channel FPI+.","annote":"","author":[{"family":"Pfüller","given":"Enrico"},{"family":"Wolf","given":"Jürgen"},{"family":"Schindler","given":"Karsten"},{"family":"Person","given":"Michael J."}],"citation-label":"Pfueller2018","collection-editor":[],"collection-title":"","container-author":[],"container-title":"Proc. SPIE","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2018"]],"literal":"2018"},"event-place":"","id":"0d1867933896c048069ff6b741cb0bfdasteroidguy","interhash":"5256c3dcc35041f8c06abac9a0903056","intrahash":"0d1867933896c048069ff6b741cb0bfd","issue":"","issued":{"date-parts":[["2018"]],"literal":"2018"},"keyword":"SOFIA myown","misc":{"doi":"10.1117/12.2313663"},"note":"","number":"","page":"107022V","page-first":"107022","publisher":"","publisher-place":"","status":"","title":"Adding a second spectral channel to the SOFIA FPI+ science instrument","type":"article-journal","username":"asteroidguy","version":"","volume":"10702"},"530b988ca6687d22a9dcf1c76f919084asteroidguy":{"DOI":"10.1117/12.2237207","ISBN":"","ISSN":"","URL":"https://www.dsi.uni-stuttgart.de/institut/mitarbeiter/schindler/Wolf_et_al._2016.pdf","abstract":"The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5-meter infrared telescope built into a Boeing 747SP. In 2014 SOFIA reached its “Full Operational Capability” milestone and nowadays takes off about three times a week to observe the infrared sky from altitudes above most of the atmosphere's water vapor content. Despite reaching this major milestone, efforts to improve the observatory's performance are continuing in many areas. The team of the Deutsches SOFIA Institut, DSI (German SOFIA Institute) at the SOFIA Science Center in Moffett Field, CA works in several engineering areas to improve the observatory's performance and its efficiency. DSI supports the allocation process of SOFIA's observation time for guest observers, provides and supports two facility science instruments and conducts an observing program of stellar occultations by small objects of the solar system. This paper summarizes results and ongoing work on a spare secondary mirror made of aluminum, the new and improved Focal Plane Imager (FPI+) that has become a facility science instrument, the Field-Imaging Far-Infrared Line Spectrometer (FIFI-LS), new cameras and optics for the Fine Field and Wide Field Imagers (FFI+ and WFI+), real-time astrometric solution of star field images, ground support equipment and astronomical observations.","annote":"","author":[{"family":"Wolf","given":"Jürgen"},{"family":"Colditz","given":"Sebastian"},{"family":"Lachenmann","given":"Michael"},{"family":"Pfüller","given":"Enrico"},{"family":"Schindler","given":"Karsten"},{"family":"Wiedemann","given":"Manuel"},{"family":"Zinnecker","given":"Hans"},{"family":"Krabbe","given":"Alfred"}],"citation-label":"Wolf2016","collection-editor":[],"collection-title":"","container-author":[],"container-title":"Proc. SPIE","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2016"]],"literal":"2016"},"event-place":"","id":"530b988ca6687d22a9dcf1c76f919084asteroidguy","interhash":"e7ba662515119ff172ad181b1ff822e7","intrahash":"530b988ca6687d22a9dcf1c76f919084","issue":"","issued":{"date-parts":[["2016"]],"literal":"2016"},"keyword":"ATUS SOFIA myown","misc":{"doi":"10.1117/12.2237207"},"note":"","number":"","page":"99730J-99730J-14","page-first":"99730","publisher":"","publisher-place":"","status":"","title":"Deutsches SOFIA Institut (DSI) at the SOFIA Science Center: engineering and scientific contributions to the airborne observatory","type":"article-journal","username":"asteroidguy","version":"","volume":"9973"},"0a85c83e74fd2b2d3ea8ea3f956c9facasteroidguy":{"DOI":"10.1117/12.2231531","ISBN":"","ISSN":"","URL":"https://www.dsi.uni-stuttgart.de/institut/mitarbeiter/schindler/Schindler_et_al._2016.pdf","abstract":"SOFIA is an airborne observatory, operating a gyroscopically stabilized telescope with an effective aperture of 2.5 m on-board a modified Boeing 747SP. Its primary objective is to conduct observations at mid- to far-infrared wavelengths. When SOFIA opens its door to the night sky, the initial telescope pointing is estimated from the aircraft's position and heading as well as the telescope's attitude relative to the aircraft. This initial pointing estimate needs to be corrected using stars that are manually identified in tracking camera images; telescope pointing also needs to be verified and refined at the beginning of each flight leg. We report about the implementation of the astrometry.net package on the telescope operator workstations on-board SOFIA. This package provides a very robust, reliable and fast algorithm for blind astrometric image calibration. Using images from SOFIA's Wide Field Imager, we are able to display an almost instant, continuous feedback of calculated right ascension, declination and field rotation in the GUI for the telescope operator. The computer-aided recognition of star patterns will support telescope pointing calibrations in the future, further increasing the efficiency of the observatory. We also discuss other current and future use cases of the astrometry.net package in the SOFIA project and at the German SOFIA Institute (DSI).","annote":"","author":[{"family":"Schindler","given":"Karsten"},{"family":"Lang","given":"Dustin"},{"family":"Moore","given":"Liz"},{"family":"Hümmer","given":"Martin"},{"family":"Wolf","given":"Jürgen"},{"family":"Krabbe","given":"Alfred"}],"citation-label":"Schindler2016","collection-editor":[],"collection-title":"","container-author":[],"container-title":"Proc. SPIE","documents":[],"edition":"","editor":[],"event-date":{"date-parts":[["2016"]],"literal":"2016"},"event-place":"","id":"0a85c83e74fd2b2d3ea8ea3f956c9facasteroidguy","interhash":"d101b4bfdad6196a739a6c97a6922014","intrahash":"0a85c83e74fd2b2d3ea8ea3f956c9fac","issue":"","issued":{"date-parts":[["2016"]],"literal":"2016"},"keyword":"ATUS SOFIA myown","misc":{"doi":"10.1117/12.2231531"},"note":"","number":"","page":"991307-991307-14","page-first":"991307","publisher":"","publisher-place":"","status":"","title":"Computer-aided star pattern recognition with astrometry.net: in-flight support of telescope operations on SOFIA","type":"article-journal","username":"asteroidguy","version":"","volume":"9913"}}