Mt.Evans Observatory News: NOTE ON THE RECENTLY COMPLETED CONSTRUCTION-- The completion of the 2,100 square foot all-steel building, designed to withstand 200 mph winds, during the remarkably short construction season at 14,000 ft is testimonial to the skill and expertise of the contractors involved in the effort. We are happy to cite the following: Architect/Designer: Robert Armon/Patrick Meyer Engineering: Gerald Schlegel General Contractor: J.P. Meyer Trucking & Construction Project Manager: James Greathead Observatory Director: Professor Robert E. Stencel Subcontractors: Special thanks to: B & C Steel US Forest Service M & D Construction Clear Creek County All Energy Electric Ash Manufacturing A & L Sheet Metal Friends of Chamberlin Observatory B & M Roofing Front Range Astronomers Mile High Body Shop Merlin Controls Corp. Mobile Premix Lightning Protection Inc. RG Insulators Van Dyke Engineering Colorado Doorways Hi Plains Trucking THE OBSERVATORY-- DU's claim to have the "world's highest operating observatory" is based on the official observatories listing that appears in the Astronomical Almanac. At 4,313 meters (Georgetown, CO), we are nearly 100 meters above the highest point listed for Mauna Kea (4,215 m), the nearest competitor. Still higher sites are either proposed or closed, but nothing else in North America comes close. The observatory is operated under a Special Use Permit granted by the USDA Forest Service. The topography, which includes a steep ridge immediately upwind, favors excellent seeing conditions. Sub-arcsecond seeing has been measured, and both acoustic sounding and differential image motion monitoring suggest atmospheric cells sizes of order one meter. The Meyer Foundation recognized these advantages and selected Mt.Evans for installation of their unique Meyer Binocular Telescope. To take advantage of the high altitude, the building and telescope design incorporate airflow and thermal management strategies. The building is rounded to slip thru the prevailing westerly winds, with the dome located in the upwind side. The dome is elevated 40 feet to place the telescope above as much of the ground-layer turbulence as possible. The cylinder wall that supports the dome has eight adjustable windows and vents to further manage airflow in and around the main slit of the 22'6" Ash Dome. Inside the dome room, a false floor has been installed with airflow grates that connect to a underfloor plenum and a 4000 cfm air handing unit in the room below. The airhandling unit exhaust is ducted to the east soffit end of the building, so that air can be drawn from the dome room to prevent "packing" and turbulence in front of the telescope optics. The system can be reverse to provide positive pressure into the dome room as well, should that prove more effective in managing "dome seeing". The telescope tubes themselves include 4 exhaust fans each mounted around the mirror cells, to draw a steady stream of air into the tubes and across the mirrors and out, to stabilize "tube seeing" insofar as possible. Thermal management is accomplished with the circulation of an antifreeze solution thru pipes that surround the entire mount, yoke and tube structures, plus inside the mirror cells. The fluid is pumped thru a heat exchange plenum inside the airhandling unit, to insure the fluid and hence the telescope temperature is kept close to air temperature (within one degree). The mirror cells also contain a set of three Peltier coolers in contact with the fluid, and these can be independently adjusted to heat or cool the mirrors, to minimize the telescope contribution overall seeing. The 28.5 inch Zerodur mirrors are finished to 20th wave accuracy by Contraves. They are overcoated with a multi-layer dielectric enhanced silver, providing high reflectance from the near UV to well into the infrared. A low order adaptive optics system for one half of the Meyer Binocular Telescope, based on simple optics and commercially available key components, has been designed and built. For this 0.7 meter aperture telescope, (D/ro) is small enough even in the visible spectral region, that only five correction orders (tip, tilt, defocus and 2 aberrations) are required to produce significantly improved images. The system designed by Donald Bruns, called the AO-5, uses translating lenses to produce smooth aberration corrections. A large format CCD camera will be attached to this device for the final imaging step. The telescope control system has been designed and built by Merlin Controls Corporation, and uses high precision encoders and software to enable arcminute pointing accuracy even following180 degree slew motions. The control system interfaces with Software Bisque's THE SKY to further ease object identification and acquisition, and lend itself to remote operational control. The high altitude is conducive to infrared astronomy in particular. Average water vapor columns are 5 mm in summer and less than 1 mm in winter, providing for infrared transparency to 27 microns and in the submillimeter regions. At Denver University, we are emphasizing this use for the observatory, and have constructed two instruments that make use of new infrared array technology. TNTCAM is a mid-IR camera capable of imaging in 8 different filters between 5 and 24 microns, onto a 128 x 128 Rockwell Si:As hybrid array. TNTCAM has been in service since 1995, especially providing Jupiter monitoring support for the NASA Galileo probe, with observing time at the Wyoming Infrared Observatory. TGIRS is a new twin grating IR spectrometer, using the same array, is capable of obtaining medium-high resolution spectra between 7 and 13 microns. This spectrograph will concentrate on silicate dust features in highly evolved stars. The educational mission of the University of Denver permits us to plan the eventual remote access of the new telescope via astronomers and students over computer networks. In principle, the line of sight between campus and mountain permit a microwave link for real time communication and control, and subsequent interface to the internet or similar networks. Also, we invite collaborative research proposals, with cost sharing, from professional astronomers. Observing proposals from amateur astronomers who are members of Astronomical League affiliated clubs will also be considered. Procedures concerning these arrangements will appear on our web pages: www.du.edu/physastron/obs.html. More background-- A brief history of Mt.Evans developments -- 1932 Arthur Compton performs first cosmic ray measurements 1936 Bruno Rossi demonstrates time dilation effects with mu mesons 1950s DU-led, international cosmic ray studies conducted on Mt.Evans 1972 "NASA" 24 inch telescope installed 1994 Observatory upgrade proposed , begin Environmental Impact study 1995 Project approved, foundation installed before autumn 1996 Building completed, telescope installed before autumn 1997 First light anticipated Notes concerning the high altitude site-- Mt.Evans is a 14,268 ft elevation peak situated in the Front Range of the Rocky Mountains, Colorado. It's relative isolation, approximately 15 miles east of the continental divide, provide some degree of drier, less cloudy and less windy conditions than those familiar to ski resort visitors. The new observatory is situated on a special use parcel near the end of the 14 mile paved state highway to the summit, and sits at 14,125 ft at its base, rising to a 14,165 ft apex. The University of Denver has conducted scientific programs atop Mt.Evans since the 1930s, and between anecdotal reports and the remote weather station data collected since 1992, reasonably complete descriptions now exist for annual variations in temperature, winds, humidity, snowfall patterns, sunlight and cloud cover. Conditions can become brutal at times, as atop any high mountain, but when conditions are favorable, they can be world- class quality for astronomy. As reported at recent meetings of the American Astronomical Society, astronomically useful conditions are observed more than 60% of the nights (about half of these photometric), and winds average 20-30 mph from the west- southwest direction, with highest winds noted in spring and autumn season changes (80 mph maximum). Although situated within line of sight of a major metropolitan area, the 10,000 ft elevation gain over Denver helps limit the amount of light pollution that reaches the observatory view of the sky. Sky brightness measurements made in September 1994 found 21.5 mag/sq.arcsec, V band, zenith, which is only 0.5 mag brighter than the naturally occurring background at all sites. Astronomical seeing, based on double stars, differential image motion monitoring and acoustic sounding, averages under one arcsecond. Infrared transparency to 27 microns has been characterized. Major challenges still facing the observatory include development of remote control, safe and reliable winter access and alternative power sources. Monetary or equipment donations to help us address these challenges is welcome. Science objectives-- Some of the science problems the dual aperture telescope is uniquely situated to tackle include the study of planetary atmosphere, detection of planetary systems around nearby stars and the analysis of evolutionary changes in stars. Among the research projects planned after the Meyer Binocular Telescope is installed include: -- infrared imaging and spectroscopy of the planets -- such studies will better characterize the atmospheric conditions of these bodies and the relation of atmospheric conditions elsewhere to earth's weather systems; --studies of members of our outer solar system, including comets and Kuiper Belt objects -- these denizens of deep space record the origin and evolution of our solar system in ways not seen among the inner planets; such studies will help characterize their numbers and orbital motions; --studies of the birth and death of stars and their planetary systems, because infrared observations have discovered increasingly strong evidence for planetary systems around other stars, which require careful followup studies to verify and to determine the relationship between the evolutionary state of the central star and the "viability" of the planetary system; --surveys for novae, supernovae, clusters, active galaxies and other astrophysical phenomena -- as the recent Jupiter-comet collision indicated, explosive events occur from time to time and only telescopes in excellent locations are prepared to fully explore these events. PRESENT STATUS -- At this writing, unusually heavy late September snows have closed the road to vehicles. This month-earlier-than-usual closure prevented us from installing the telescope optics and control systems. Altho oversnow vehicles can reach the summit, such expeditions are not trivial or conducive to the type of hauling and detail work still to be done. However, work can resume in late spring when the snows normally subside. We hope to achieve "first light" during summer 1997.