MICADO is the near-Ir imaging camera for the multi-conjugate adaptive optics system on the external link42-m European Extremely Large Telescope. Following a call for proposals by ESO, the MICADO Consortium was awarded the contract for the Phase A study. The goal of the consortium is to design a simple and robust instrument that can address as much science as possible, and be ready in time for first light at the E-ELT. The instrument PI is R. Genzel, Project Manager is R. Davies and Project Scientist A. Renzini.
|Figure 1: Overview of the mechanical design of MICADO. Left: the full cryostat; Right: the large filter wheels for both arms of the instrument.|
The current instrument concept combines a simple and robust primary imaging field with a configurable "Christmas Tree" Arm.
The primary imaging field uses almost exclusively reflective optics to image a field of approximately 53"x53". The only
transmissive optics are the necessary entrance window and filters. The filters wheels, are the only moving part in this
arm of the camera. The pixel scale is fixed at 3mas, and so the detectors at the focal plane need to provide 16000x16000 pixels.
The Christmas Tree arm picks off a field of approximately 8"x8" adjacent to the primary imaging field covered by a single 4Kx4K detector. The light path is folded along an independent optical path and, via a number of exchangeable fold mirrors, can be imaged at variable pixel scales. The baseline is to provide 2mas scale, yielding fields of view of 8". Two large wheels provide space for numerous filters as well as options for polarimetry, spectroscopy, etc. The possibility of including a tunable narrow band filter (Fabry Perot) is also being considered. The detailed capabilities that will be included in this arm are under review by the Science Team and will be decided early during Phase A2.
MICADO will have a combination of angular resolution, field of view, and near-IR sensitivity that will be unsurpassed by any other imager on the ground or in space. As a long-slit spectrograph, it will offer for some years an unsurpassed combination of angular and spectral resolution and sensitivity. These capabilities open to MICADO many opportunities for breaking new ground in several areas of cosmology and astrophysics.
The performances of MICADO make it the ideal instrument to study the nuclei of galaxies, closer to their centers than ever done so far. This applies first to the Galactic Center itself, with the possibility of mapping stellar orbits and flaring gas closer and closer to the event horizon of the central BH.
The impressive resolution (6 or 7 times better than JWST) and sensitivity (to an AB magnitude of about 29 across I-K) of MICADO will provide exquisite detail over a range of science themes from young stellar objects in our galaxy to star formation in high redshift galaxies.
The superior angular resolution of MICADO makes its astrometric applications especially attractive, and every effort should be made to ensure the short and long term stability of the instrument. Besides mapping stellar orbits near the central black hole in the Galaxy, astrometry of globular cluster stars should allow astronomers to measure trigonometric parallaxes and proper motions of these stellar systems with unprecedented accuracy, as well as reveal whether they harbour intermediate mass black holes near their centers.
The Observatory has an important role mainly in two areas: Optical design of the camera and development and coordination of science cases. Specific science cases are described in : LINK1, LINK2.