In the previous Newsletter, I described the increased participation by NSO scientific staff in the efforts to develop a successful proposal for a large visible/infrared telescope. The resulting task groups have been very active since then, involving a number of participants from outside NSO as well. The science task group in particular has concentrated its efforts on defining the scientific targets for the facility, deriving from those targets the required parameters for the telescope. This effort assumed special urgency due to the aggressive review schedule of the Space Studies Board Task Group on Ground-Based Solar Research (the "Parker Committee"). As a result, a report on the science goals has been prepared and the NSO staff has agreed on the parameters for the facility (300 cm aperture; visible and full IR coverage; adaptive optics; best site; 3 arcmin field-of-view; low scattered light coronagraphic, provided the cost impact does not exceed 10%). In parallel, an interim technical report is available on the feasibility study for the CLEAR (Coronagraphic and Low Emissivity Astronomical Reflector) facility.
Adaptive optics is a major capability requirement for any future large solar telescope. Thomas Rimmele and Rich Radick recently reported the successful implementation of the Sac Peak Vacuum Tower Telescope active optics system, which is able to correct the remaining telescope optics aberrations. This capability presents major progress in the development of adaptive optics at NSO. It demonstrates our ability to do wavefront sensing on the extended, low-contrast object that is the solar image. Together with the earlier demonstrated ability to do rapid tip-tilt correction, this sets the stage for the implementation of a full-up adaptive optics system. In a joint program, the NSO and the USAF team at Sac Peak have embarked on a high-priority program to build a 20 Zernike adaptive optics system at the VTT in the next two to three years.
Unfortunately, there is no news to report on the SOLIS initiative. We don't expect a new start until FY 1998. At Sac Peak everything is in full progress in the implementation of the USAF ISOON prototype.
Jacques M. Beckers