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Session 67 - New Solar Instrumentation.
Oral session, Wednesday, June 12
Wisconsin Center,
Whereas optical nighttime is undergoing a revolution with the deployment of very large ground-based telesecopes in the 6.5 to 10 meter class, solar telescope technology has stagnated at the meter class aperture level. Space and balloon borne solar telescopes are now being built and planned in this aperture range. Are they likely to take over most of the roles of these ground-based facilities? There is undoubtedly a need for solar telescopes with larger apertures to explore important solar physics issues which require the highest possible angular resolution, high sensitivity, full visible and infrared wavelength coverage and low scattered light.
Using advances in astronomical telescope technologies at optical and X-ray wavelengths, we (NSO staff together with engineering and scientific working group) are undertaking a feasibility study of a 4-meter class solar telescope with these qualities. Such a powerful, special purpose telescope will find many applications in other areas of astronomy in which low scattered light coronagraphic properties are at a premium. Since the telescope technologies needed to achieve these are similar to those needed for low emissivity telescopes, the telescope concept has been labelled CLEAR = Coronagraphic and Low Emissivity Astronomical Reflector. CLEAR will have a 5 arcmin diameter field-of-view (the size of a solar active region), wavelength coverage of at least 0.38 to 15 microns (including all of the visible and infrared solar spectral lines and regions of interest), low and constant polarization (enabling accurate and precise magnetic field observations), and scattered light low enough to enable studies of the coronal magnetic fields and coronal fine structure. It will include coud, Nasmyth and Gregorian focal stations for a variety of instruments. Its unobstructed aperture will allow optimum imaging, which will be enhanced by the incorporation of adaptive optics.
In my lecture I will review the science drivers for CLEAR, and give a progress report on a feasibility study now underway. The scientific and technical goals set for CLEAR require a number new innovative technological solutions. These will be described and discussed. The siting of CLEAR is an important aspect of the study. I will review our present knowledge of possible solar observatory sites for CLEAR.
