Dr. Sebastian Schäfer Profile

Dr. Sebastian Schäfer

Senior Scientist at Georg-August-Univ Göttingen

SPIE Involvement:

Author

Publications (14)

SPIE Journal Paper | 15 November 2023

Toward 10 cm s⁻¹ radial velocity accuracy on the Sun using a Fourier transform spectrometer

Michael Debus, Sebastian Schäfer, Ansgar Reiners

JATIS, Vol. 9, Issue 04, 045003, (November 2023) https://doi.org/10.1117/12.10.1117/1.JATIS.9.4.045003

KEYWORDS: Calibration, Fourier transforms, Iodine cells, Temperature metrology, Iodine, Sensors, Light sources, Vacuum, Thermal stability, Spectroscopy

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Proceedings Article | 29 August 2022 Presentation + Paper

ANDES, the high resolution spectrograph for the ELT: science case, baseline design and path to construction

A. Marconi, M. Abreu, V. Adibekyan, V. Alberti, S. Albrecht, J. Alcaniz, M. Aliverti, C. Allende Prieto, J. D. Alvarado Gómez, P. J. Amado, M. Amate, M. I. Andersen, E. Artigau, C. Baker, V. Baldini, A. Balestra, S. A. Barnes, F. Baron, S. C. C. Barros, S. M. Bauer, M. Beaulieu, O. Bellido-Tirado, B. Benneke, T. Bensby, E. A. Bergin, K. Biazzo, A. Bik, J. L. Birkby, N. Blind, I. Boisse, E. Bolmont, M. Bonaglia, X. Bonfils, F. Borsa, A. Brandeker, W. Brandner, C. H. Broeg, M. Brogi, D. Brousseau, A. Brucalassi, J. Brynnel, L. A. Buchhave, D. F. Buscher, A. Cabral, G. Calderone, R. Calvo-Ortega, B. L. Canto Martins, F. Cantalloube, L. Carbonaro, G. Chauvin, B. Chazelas, A.-L. Cheffot, Y. S. Cheng, A. Chiavassa, L. Christensen, R. Cirami, N. J. Cook, R. J. Cooke, I. Coretti, S. Covino, N. Cowan, G. Cresci, S. Cristiani, V. Cunha Parro, G. Cupani, V. D'Odorico, I. de Castro Leão, A. De Cia, J. R. De Medeiros, F. Debras, M. Debus, O. Demangeon, M. Dessauges-Zavadsky, P. Di Marcantonio, F. Dionies, R. Doyon, J. Dunn, D. Ehrenreich, J. P. Faria, C. Feruglio, M. Fisher, A. Fontana, M. Fumagalli, T. Fusco, J. Fynbo, O. Gabella, W. Gaessler, E. Gallo, X. Gao, L. Genolet, M. Genoni, P. Giacobbe, E. Giro, R. S. Gonçalves, O. Gonzalez, J. I. González Hernández, F. Gracia Témich, M. G. Haehnelt, C. Haniff, A. Hatzes, R. Helled, H.J. Hoeijmakers, P. Huke, S. Järvinen, A. Järvinen, A. Kaminski, A. Korn, D. Kouach, G. Kowzan, L. Kreidberg, M. Landoni, A. Lanotte, A. Lavail, J. Li, J. Liske, C. Lovis, S. Lucatello, D. Lunney, M. MacIntosh, N. Madhusudhan, L. Magrini, R. Maiolino, L. Malo, A. Man, T. Marquart, E. L. Marques, A. M. Martins, C. J. A. P. Martins, P. Maslowski, C. Mason, E. Mason, R. A. McCracken, P. Mergo, G. Micela, T. Mitchell, P. Mollière, M. Monteiro, D. Montgomery, C. Mordasini, J. Morin, A. Mucciarelli, M. T. Murphy, M. N'Diaye, B. Neichel, A. T. Niedzielski, E. Niemczura, L. Nortmann, P. Noterdaeme, N. Nunes, L. Oggioni, E. Oliva, H. Önel, L. Origlia, G. Östlin, E. Palle, P. Papaderos, G. Pariani, J. Peñate Castro, F. Pepe, L. Perreault Levasseur, P. Petit, L. Pino, J. Piqueras, A. Pollo, K. Poppenhaeger, A. Quirrenbach, E. Rauscher, R. Rebolo, E. M. A. Redaelli, S. Reffert, D. T. Reid, A. Reiners, P. Richter, M. Riva, S. Rivoire, C. Rodríguez-López, I. U. Roederer, D. Romano, S. Rousseau, J. Rowe, S. Salvadori, N. Santos, P. Santos Diaz, J. Sanz-Forcada, M. Sarajlic, J.-F. Sauvage, S. Schäfer, R. P. Schiavon, T. M. Schmidt, C. Selmi, S. Sivanandam, M. Sordet, R. Sordo, F. Sortino, D. Sosnowska, S. G. Sousa, E. Stempels, K. G. Strassmeier, A. Suárez Mascareño, A. Sulich, X. Sun, N.R. Tanvir, F. Tenegi-Sanginés, S. Thibault, S. J. Thompson, A. Tozzi, M. Turbet, P. Vallée, R. Varas, K. Venn, J.-P. Véran, A. Verma, M. Viel, G. Wade, C. Waring, M. Weber, J. Weder, B. Wehbe, J. Weingrill, M. Woche, M. Xompero, E. Zackrisson, A. Zanutta, M. R. Zapatero Osorio, M. Zechmeister, J. Zimara

Proceedings Volume 12184, 1218424 (2022) https://doi.org/10.1117/12.2628689

KEYWORDS: Physics, Spectrographs, Stars, Astronomy, Galactic astronomy, Astrophysics, Exoplanets, Planets, Spectral resolution, Absorption

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Proceedings Article | 29 August 2022 Poster + Paper

A near-infrared Fabry-Pérot for Fourier-transform spectrograph calibration

M. Debus, S. Schäfer, P. Huke, A. Reiners

Proceedings Volume 12184, 121844U (2022) https://doi.org/10.1117/12.2629912

KEYWORDS: Fourier transforms, Calibration, Fiber couplers, Mirrors, Sun, Optical benches, Light emitting diodes, Reflectivity, Spectrographs, Light sources

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Proceedings Article | 25 August 2022 Poster + Paper

ExoTOM: a target-observation-manager automating exoplanet transit follow-up

Tilman Masur, Tim-Oliver Husser, Sebastian Schäfer, Stefan Dreizler, Rachel Street

Proceedings Volume 12186, 121861O (2022) https://doi.org/10.1117/12.2628823

KEYWORDS: Photometry, Telescopes, Exoplanets, Data analysis

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Proceedings Article | 13 December 2020 Poster + Paper

Observing the integrated and spatially resolved Sun with ultra-high spectral resolution

S. Schäfer, K. Royen, A. Huster Zapke, M. Ellwarth, A. Reiners

Proceedings Volume 11447, 11447A9 (2020) https://doi.org/10.1117/12.2560156

KEYWORDS: Sun, Spectral resolution, Spectrographs, Calibration, Spectroscopes, Astrophysics, Observatories, Telescopes, Fourier transforms, Frequency combs

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Proceedings Article | 13 December 2020 Poster + Paper

Fiber-coupling of Fourier transform spectrographs

S. Schäfer, P. Huke, D. Meyer, A. Reiners

Proceedings Volume 11447, 114473Q (2020) https://doi.org/10.1117/12.2561599

KEYWORDS: Fourier transforms, Spectrographs, Optical fibers, Calibration, Astronomy, Iterated function systems, Light sources, Beam shaping

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Proceedings Article | 12 July 2018 Paper

ELT -HIRES the High Resolution Spectrograph for the ELT: Fabry-Pérots for use as calibration sources

Philipp Huke, Sebastian Schäfer, Ansgar Reiners, Ulf Seemann, Marco Riva, Francesco Pepe, Bruno Chazelas, Piotr Masłowski, Grzegorz Kowzan, Richard McCracken, Derryck Reid

Proceedings Volume 10702, 107029L (2018) https://doi.org/10.1117/12.2313394

KEYWORDS: Calibration, Spectrographs, Fourier transforms, Spectroscopy, Precision calibration, Spectral calibration

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Proceedings Article | 11 July 2018 Paper

The MICADO first light imager for the ELT: preliminary design of the MICADO Calibration Assembly

G. Rodeghiero, J.-U. Pott, N. Münch, R.-R. Rohloff, U. Grözinger, E. Biancalani, M. Sawczuck, M. Häberle, J. Moreno-Ventas, S. Schäfer, U. Seemann, V. Naranjo, S. Barboza, F. Müller, R. Hofferbert, J. Ramos, L. Mohr, M. C. Cárdenas Vázquez, P. Bizenberger, C. Pernechele, M. Ebert, M. Fabricius

Proceedings Volume 10702, 107028U (2018) https://doi.org/10.1117/12.2311721

KEYWORDS: Calibration, Lamps, Prototyping, Manufacturing, Light sources, Sensors, Mirrors, Imaging spectroscopy, Adaptive optics, Telescopes

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Proceedings Article | 9 July 2018 Paper

Two Fabry-Pérots and two calibration units for CARMENES

Sebastian Schäfer, Eike Guenther, Ansgar Reiners, Johannes Winkler, Michael Pluto, Jörg Schiller

Proceedings Volume 10702, 1070276 (2018) https://doi.org/10.1117/12.2315241

KEYWORDS: Calibration, Spectrographs, Near infrared, Temperature metrology

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Proceedings Article | 26 June 2017 Paper

Phase A: calibration concepts for HIRES

Philipp Huke, Livia Origlia, Marco Riva, Jake Charsley, Richard McCracken, Derryck Reid, Grzegorz Kowzan, Piotr Maslowski, Karen Disseau, Sebastian Schäfer, Christopher Broeg, Mirsad Sarajlic, François Dolon, Heidi Korhonen, Ansgar Reiners, Isabelle Boisse, Sandrine Perruchot, Sebastien Ottogalli, Francesco Pepe, Ernesto Oliva

Proceedings Volume 10329, 103292M (2017) https://doi.org/10.1117/12.2271782

KEYWORDS: Atmospheric physics, Calibration, Spectroscopes, Spectrographs, Frequency combs, Spectral calibration, Optical components

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Proceedings Article | 10 July 2014 Paper

CARMENES instrument overview

A. Quirrenbach, P. Amado, J. Caballero, R. Mundt, A. Reiners, I. Ribas, W. Seifert, M. Abril, J. Aceituno, F. J. Alonso-Floriano, M. Ammler-von Eiff, R. Antona Jiménez, H. Anwand-Heerwart, M. Azzaro, F. Bauer, D. Barrado, S. Becerril, V. J. Béjar, D. Benítez, Z. Berdiñas, M. Cárdenas, E. Casal, A. Claret, J. Colomé, M. Cortés-Contreras, S. Czesla, M. Doellinger, S. Dreizler, C. Feiz, M. Fernández, D. Galadí, M. Gálvez-Ortiz, A. García-Piquer, M. García-Vargas, R. Garrido, L. Gesa, V. Gómez Galera, E. González Álvarez, J. González Hernández, U. Grözinger, J. Guàrdia, E. Guenther, E. de Guindos, J. Gutiérrez-Soto, H.-J. Hagen, A. Hatzes, P. Hauschildt, J. Helmling, T. Henning, D. Hermann, L. Hernández Castaño, E. Herrero, D. Hidalgo, G. Holgado, A. Huber, K. Huber, S. Jeffers, V. Joergens, E. de Juan, M. Kehr, R. Klein, M. Kürster, A. Lamert, S. Lalitha, W. Laun, U. Lemke, R. Lenzen, Mauro López del Fresno, B. López Martí, J. López-Santiago, U. Mall, H. Mandel, E. Martín, S. Martín-Ruiz, H. Martínez-Rodríguez, C. Marvin, R. Mathar, E. Mirabet, D. Montes, R. Morales Muñoz, A. Moya, V. Naranjo, A. Ofir, R. Oreiro, E. Pallé, J. Panduro, V.-M. Passegger, A. Pérez-Calpena, D. Pérez Medialdea, M. Perger, M. Pluto, A. Ramón, R. Rebolo, P. Redondo, S. Reffert, S. Reinhardt, P. Rhode, H.-W. Rix, F. Rodler, E. Rodríguez, C. Rodríguez-López, E. Rodríguez-Pérez, R.-R. Rohloff, A. Rosich, E. Sánchez-Blanco, M. Sánchez Carrasco, J. Sanz-Forcada, L. Sarmiento, S. Schäfer, J. Schiller, C. Schmidt, J. H. M. M. Schmitt, E. Solano, O. Stahl, C. Storz, J. Stürmer, J. Suárez, R. Ulbrich, G. Veredas, K. Wagner, J. Winkler, M. Zapatero Osorio, M. Zechmeister, F. Abellán de Paco, G. Anglada-Escudé, C. del Burgo, A. Klutsch, J. Lizon, M. López-Morales, J. Morales, M. A. C. Perryman, S. Tulloch, W. Xu

Proceedings Volume 9147, 91471F (2014) https://doi.org/10.1117/12.2056453

KEYWORDS: Spectrographs, Optical fibers, Lamps, Stars, Telescopes, Calibration, Planets, Sensors, Visible radiation, Exoplanets

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This paper gives an overview of the CARMENES instrument and of the survey that will be carried out with it during the first years of operation. CARMENES (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrographs) is a next-generation radial-velocity instrument under construction for the 3.5m telescope at the Calar Alto Observatory by a consortium of eleven Spanish and German institutions. The scientific goal of the project is conducting a 600-night exoplanet survey targeting ~ 300 M dwarfs with the completed instrument. The CARMENES instrument consists of two separate echelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. The spectrographs are housed in vacuum tanks providing the temperature-stabilized environments necessary to enable a 1 m/s radial velocity precision employing a simultaneous calibration with an emission-line lamp or with a Fabry-Perot etalon. For mid-M to late-M spectral types, the wavelength range around 1.0 μm (Y band) is the most important wavelength region for radial velocity work. Therefore, the efficiency of CARMENES has been optimized in this range. The CARMENES instrument consists of two spectrographs, one equipped with a 4k x 4k pixel CCD for the range 0.55 - 1.05 μm, and one with two 2k x 2k pixel HgCdTe detectors for the range from 0.95 - 1.7μm. Each spectrograph will be coupled to the 3.5m telescope with two optical fibers, one for the target, and one for calibration light. The front end contains a dichroic beam splitter and an atmospheric dispersion corrector, to feed the light into the fibers leading to the spectrographs. Guiding is performed with a separate camera; on-axis as well as off-axis guiding modes are implemented. Fibers with octagonal cross-section are employed to ensure good stability of the output in the presence of residual guiding errors. The fibers are continually actuated to reduce modal noise. The spectrographs are mounted on benches inside vacuum tanks located in the coud´e laboratory of the 3.5m dome. Each vacuum tank is equipped with a temperature stabilization system capable of keeping the temperature constant to within ±0.01°C over 24 hours. The visible-light spectrograph will be operated near room temperature, while the near-IR spectrograph will be cooled to ~ 140 K. The CARMENES instrument passed its final design review in February 2013. The MAIV phase is currently ongoing. First tests at the telescope are scheduled for early 2015. Completion of the full instrument is planned for the fall of 2015. At least 600 useable nights have been allocated at the Calar Alto 3.5m Telescope for the CARMENES survey in the time frame until 2018. A data base of M stars (dubbed CARMENCITA) has been compiled from which the CARMENES sample can be selected. CARMENCITA contains information on all relevant properties of the potential targets. Dedicated imaging, photometric, and spectroscopic observations are underway to provide crucial data on these stars that are not available in the literature.

Proceedings Article | 5 October 2012 Paper

CARMENES. I: instrument and survey overview

Andreas Quirrenbach, Pedro Amado, Walter Seifert, Miguel Sánchez Carrasco, Holger Mandel, Jose Caballero, Reinhard Mundt, Ignasi Ribas, Ansgar Reiners, Miguel Abril, Jesus Aceituno, Javier Alonso-Floriano, Matthias Ammler-von Eiff, Guillem Anglada-Escude, Regina Antona Jiménez, Heiko Anwand-Heerwart, David Barrado y Navascués, Santiago Becerril, Victor Bejar, Daniel Benitez, Concepcion Cardenas, Antonio Claret, Josep Colome, Miriam Cortés-Contreras, Stefan Czesla, Carlos del Burgo, Michaela Doellinger, R. Dorda, Stefan Dreizler, Carmen Feiz, Matilde Fernandez, David Galadi, Rafael Garrido, Jonay González Hernández, Josep Guardia, Eike Guenther, Enrique de Guindos, Juan Gutiérrez-Soto, Hans Hagen, Artie Hatzes, Peter Hauschildt, Jens Helmling, Thomas Henning, Enrique Herrero, Armin Huber, Klaus Huber, Sandra Jeffers, Viki Joergens, Enrique de Juan, M. Kehr, Alexis Klutsch, Martin Kürster, S. Lalitha, Werner Laun, Ulrike Lemke, Rainer Lenzen, Jean-Louis Lizon, Mauro López del Fresno, Mercedes López-Morales, Javier López-Santiago, Ulrich Mall, Eduardo Martin, Susana Martín-Ruiz, Eduard Mirabet, David Montes, Juan Carlos Morales, Rafael Morales Muñoz, Andres Moya, Vianak Naranjo, Raquel Oreiro, David Pérez Medialdea, Michael Pluto, Ovidio Rabaza, Alejandro Ramon, Rafael Rebolo, Sabine Reffert, Petra Rhode, Hans-Walter Rix, Florian Rodler, Eloy Rodríguez, Cristina Rodríguez López, Emilio Rodríguez Pérez, A. Rodriguez Trinidad, Ralf-Reiner Rohloff, Ernesto Sánchez-Blanco, Jorge Sanz-Forcada, Sebastian Schäfer, Jörg Schiller, Christof Schmidt, Jürgen Schmitt, Enrique Solano, Otmar Stahl, Clemens Storz, Julian Stürmer, Juan Carlos Suarez, Ulrich Thiele, Rainer Ulbrich, Manuela Vidal-Dasilva, Karl Wagner, Johannes Winkler, Wenli Xu, Maria Rosa Zapatero Osorio, Mathias Zechmeister

Proceedings Volume 8446, 84460R (2012) https://doi.org/10.1117/12.925164

KEYWORDS: Stars, Lamps, Planets, Spectrographs, Optical fibers, Calibration, Sensors, Telescopes, Exoplanets, Near infrared

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Proceedings Article | 24 September 2012 Paper

Two Fabry-Perot interferometers for high precision wavelength calibration in the near-infrared

Sebastian Schäfer, Ansgar Reiners

Proceedings Volume 8446, 844694 (2012) https://doi.org/10.1117/12.926232

KEYWORDS: Calibration, Spectrographs, Lamps, Fabry–Perot interferometry, Near infrared, Fabry–Perot interferometers, Precision calibration, Planets, Mirrors, Infrared radiation

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Proceedings Article | 13 September 2012 Paper

A high-resolution Fourier transform spectrometer for astronomical observations and development of wavelength standards

Ulrike Lemke, Ansgar Reiners, Sebastian Schäfer

Proceedings Volume 8450, 845047 (2012) https://doi.org/10.1117/12.981589

KEYWORDS: Fourier transforms, Standards development, Lamps, Mirrors, Calibration, Astronomy, Planets, Near infrared, Absorption, Spectrographs

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