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 (www.universe-cluster.de).


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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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