Experimental Astronomy

, Volume 38, Issue 1–2, pp 213–248 | Cite as

The 64 Mpixel wide field imager for the Wendelstein 2m telescope: design and calibration

  • Ralf Kosyra
  • Claus Gössl
  • Ulrich Hopp
  • Florian Lang-Bardl
  • Arno Riffeser
  • Ralf Bender
  • Stella Seitz
Original Article


The Wendelstein Observatory of Ludwig Maximilians University of Munich has recently been upgraded with a modern 2m robotic telescope. One Nasmyth port of the telescope has been equipped with a wide-field corrector which preserves the excellent image quality (<0.8 median seeing) of the site (Hopp et al. 2008) over a field of view of 0.7 degrees diameter. The available field is imaged by an optical imager (WWFI, the Wendelstein Wide Field Imager) built around a customized 2×2 mosaic of 4k×4k 15 μm e2v CCDs from Spectral Instruments. This paper provides an overview of the design and the WWFI’s performance. We summarize the system mechanics (including a structural analysis), the electronics (and its electromagnetic interference (EMI) protection) and the control software. We discuss in detail detector system parameters, i.e. gain and readout noise, quantum efficiency as well as charge transfer efficiency (CTE) and persistent charges. First on sky tests yield overall good predictability of system throughput based on lab measurements.


Astronomical instrumentation Instrumentation: detectors Telescopes Charge coupled devices 



The authors thank Johannes Koppenhoefer and Mihael Kodric for their support with the data reduction process with the WWFI. Furthermore we thank Daniel Gruen for helpful discussions regarding charge transfer efficiency. We also thank Michael Schmidt and Christoph Ries, the night observers at the Wendelstein Observatory for taking the necessary data for our on-sky calibration. Michael Schmidt also took the responsibility for wiring our imager, and we thank him for doing so. We thank Wolfgang Mitsch for giving invaluable advice on configuring the electronics of our camera. We acknowledge the constructive discussion with Dietrich Baade and Olaf Iwert (ESO). This research was supported by the DFG cluster of excellence Origin and Structure of the Universe (


  1. 1.
    An, D., Johnson, J.A., Clem, J.L., et al.: ApJS 179, 326 (2008)ADSCrossRefGoogle Scholar
  2. 2.
    Baade, D., Meisenheimer, K., Iwert, O., et al.: Messenger 95, 15 (1999)ADSGoogle Scholar
  3. 3.
    Barrick, G.A., Ward, J., Cuillandre, J.-C.: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 8453 (2012)Google Scholar
  4. 4.
    Bertin, E., Arnouts, S.: A&AS 117, 393 (1996)ADSCrossRefGoogle Scholar
  5. 5.
    Bindel, A.: Master’s thesis, Ludwig-Maximilians-Universität München (2011)Google Scholar
  6. 6.
    Buckley, D.R.V., Longmore, A.J.: MNRAS 257, 731 (1992)ADSCrossRefGoogle Scholar
  7. 7.
    Castelli, F., Gratton, R.G., Kurucz, R.L.: A&A 318, 841 (1997)ADSGoogle Scholar
  8. 8.
    Cousins, A.W.J.: MmRAS 81, 25 (1976)ADSGoogle Scholar
  9. 9.
    Fukugita, M., Ichikawa, T., Gunn, J.E., et al.: AJ 111, 1748 (1996)ADSCrossRefGoogle Scholar
  10. 10.
    Girardi, L., Grebel, E.K., Odenkirchen, M., Chiosi, C.: A&A 422, 205 (2004)ADSCrossRefGoogle Scholar
  11. 11.
    Gössl, C.: PhD thesis, Ludwig-Maximilians-Universität München (2007)Google Scholar
  12. 12.
    Gössl, C., Bender, R., Fabricius, M., et al.: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 8446 (2012)Google Scholar
  13. 13.
    Gössl, C., Bender, R., Grupp, F., et al.: in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 7735 (2010)Google Scholar
  14. 14.
    Gruen, D., Seitz, S., Kosyra, R., et al.: ArXiv e-prints (2013)Google Scholar
  15. 15.
    Hayes, D.S., Latham, D.W.: ApJ 197, 593 (1975)ADSCrossRefGoogle Scholar
  16. 16.
    Hopp, U., Bender, R., Goessl, C., et al.: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 7016 (2008)Google Scholar
  17. 17.
    Hopp, U., Bender, R., Grupp, F., et al.: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 7733 (2010)Google Scholar
  18. 18.
    Iwert, O, Baade, D, Balestra, A., et al.: Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, vol. 6276 (2006)Google Scholar
  19. 19.
    Janesick, J.: Scientific Charge-Coupled Devices, Spie Press Monograph, Pm83 (Society of Photo Optical) (2001)Google Scholar
  20. 20.
    Janesick, J., Elliott, T.: Astronomical Society of the Pacific Conference Series, vol. 23, Astronomical CCD Observing and Reduction Techniques, ed. S. B. Howell, 1 (1992)Google Scholar
  21. 21.
    Johnson, H.L., Morgan, W.W.: ApJ 117, 313 (1953)ADSCrossRefGoogle Scholar
  22. 22.
    Kodric, M., Riffeser, A., Hopp, U., et al.: AJ 145, 106 (2013)ADSCrossRefGoogle Scholar
  23. 23.
    Koppenhoefer, J., Saglia, R.P., Fossati, L., et al.: MNRAS 435, 3133 (2013)ADSCrossRefGoogle Scholar
  24. 24.
    Kormendy, J., Bender, R.: ApJS 198, 2 (2012)ADSCrossRefGoogle Scholar
  25. 25.
    Kurucz, R.: ATLAS9 Stellar Atmosphere Programs and 2 km/s grid. Kurucz CD-ROM No. 13. Cambridge, Mass.: Smithsonian Astrophysical Observatory, 1993., 13 (1993)Google Scholar
  26. 26.
    Kurucz, R.L.: ApJS 40, 1 (1979)ADSCrossRefGoogle Scholar
  27. 27.
    Landolt, A.U.: AJ 78, 959 (1973)ADSCrossRefGoogle Scholar
  28. 28.
    Landolt, A.U.: AJ 88, 439 (1983)ADSCrossRefGoogle Scholar
  29. 29.
    Landolt, A.U.: AJ 104, 340 (1992)ADSCrossRefGoogle Scholar
  30. 30.
    Landolt, A.U.: AJ 137, 4186 (2009)ADSCrossRefGoogle Scholar
  31. 31.
    Lee, C.-H., Riffeser, A., Koppenhoefer, J., et al.: AJ 143, 89 (2012)ADSCrossRefGoogle Scholar
  32. 32.
    McLean, I.: Electronic Imaging in Astronomy: Detectors and Instrumentation, Springer Praxis Books / Astronomy and Planetary Sciences (Springer) (2008)Google Scholar
  33. 33.
    Oke, J.B., Gunn, J.E.: ApJ 266, 713 (1983)ADSCrossRefGoogle Scholar
  34. 34.
    Reif, K., Klink, G., Müller, P., Poschmann, H.: Astronomische Nachrichten 326, 666 (2005)ADSGoogle Scholar
  35. 35.
    Rhodes, J., Leauthaud, A., Stoughton, C., et al.: PASP 122, 439 (2010)ADSCrossRefGoogle Scholar
  36. 36.
    Schlafly, E.F., Finkbeiner, D.P.: ApJ 737, 103 (2011)ADSCrossRefGoogle Scholar
  37. 37.
    Schlegel, D.J., Finkbeiner, D.P., Davis, M.: ApJ 500, 525 (1998)ADSCrossRefGoogle Scholar
  38. 38.
    Tonry, J.L., Isani, S., Onaka, P.: Bulletin of the American Astronomical Society, vol. 39, American Astronomical Society Meeting Abstracts, 807 (2007)Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Ralf Kosyra
    • 1
    • 2
  • Claus Gössl
    • 1
  • Ulrich Hopp
    • 1
    • 2
  • Florian Lang-Bardl
    • 1
  • Arno Riffeser
    • 1
  • Ralf Bender
    • 1
    • 2
  • Stella Seitz
    • 1
    • 2
  1. 1.Universitäts-Sternwarte MünchenMünchenGermany
  2. 2.Max Planck Institut für Extraterrestrische PhysikGarchingGermany

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