Only the section on MIDI is reproduced here to full extend.
The structure of our MIDI project has now been largely established. The project will be led by the MPIA PI team (Leinert and Graser). Our Institute is responsible for the detector, the readout electronics, the cryo and vacuum system and for the complete instrument control (including VLT/VLTI environment). Our Dutch colleges will make a significant contribution, taking over all of the cold optics as well as the main part of the data evaluation software. This will be financed by the science organisation, NOVA (Co-PI is R.Waters from Amsterdam), and ASTRON in Dwingeloo, an institute experienced in instrumentation projects, will finance the optical/mechanical work. Another major contribution will come from the French, financed by INSU, with Perrin, Meudon, as Co-PI. This contribution comprises the mechanism to flatten the beam profile (e.g. by means of glass-fibres), parts of the data evaluation software, as well as co-ordinating the planning of the scientific program. The Kiepenheuer Institute in Freiburg (von der Lühe) and the Thüringer Landessternwarte, Tautenburg (Stecklum) will be involved to a lesser extent. Formal confirmation of this collaboration took place with our Dutch colleagues in May 1998, and formal confirmation is currently being prepared for the French participation. A "memorandum of understanding" has been drawn up with ESO and this is now being dealt with by the various committees within this organisation.
In 1998, we started work on the project and purchased some of the equipment. The 320×240 pixel Si:As IBC array (IBC = impurity band conduction) from Raytheon (formerly SBRC) will probably be used as detector for MIDI; the alternative detector from Boeing (formerly Rockwell) with 256×256 pixels is not yet available. The process for ordering the "science grade" detector, as well as a test detector and a multiplexer, is underway (Ligori). Work started on the development of the readout electronics in Autumn 1998 (Grimm, Salm). The computers were purchased towards the end of the year: one workstation for data collection and one for operating MIDI (including data evaluation), as well as two VME bus systems for real-time control of the instrument and synchronization with other service instruments and telescopes. (Hippler, Rauh)
The preliminary draft of the optics for the MIDI instrument was completed and submitted to the group in Dwingeloo for inspection and optimization. (Lenzen)
In order to determine the interferometric signal, the optical path for one of the two interfering beams is deliberately varied by approx. 10 µn;m by moving a pair of mirrors. The speed, accuracy and stability of the piezo adjustment unit to be used for this was investigated interferometrically in the laboratory. (Schuller)
Extensive calculations obtained with a simulation program developed by Berkefeld confirmed that the atmospherically-induced variations in the optical path length for the VLT telescopes are no more than 2 µn;m over a measurement period of 100 ms, and thus remain much smaller than the observational wavelengths. The planned measurement procedure was also simulated under "realistic conditions", ie, using noise measurements obtained with the 10 µn;m camera, MAX, at the UKIRT telescope, in order to ascertain its dependence on noise and the aperture sizes used. (Porro)
The cryogenic and vacuum concept developed for CONICA was, to a large extent, adopted for MIDI. In order to achieve the lower temperatures necessary in the mid-infrared (e.g. a detector temperature of 4 K to 7 K), the currently most powerful closed-cycle cooler was purchased. This has clear advantages over other models with regard to vibrations. (Rohloff)
Initial observations with MIDI on Paranal should be possible in 2001. (Leinert, Graser, Grimm, Herbst, Hippler, Lenzen, Ligori, Mundt, Ortlieb, Pitz, Porro, Robberto, Rohloff, Schuller, Storz, Wagner)