http://bear.ras.ucalgary.ca/CASCA/a94/gemini.html (Einblicke ins Internet, 10/1995)

Gemini Update

Gemini is a collaborative project between the USA (50%), UK (25%), Canada (15%), and Argentina, Brazil and Chile to construct an 8-m telescope on each of Mauna Kea (1998 first light) and Cerro Pachon (2000) together with a complement of instruments. The budget is strictly limited to US$176M. The telescopes will be Cassegrain only, initially f/16 with a single undersized secondary appropriate for the infrared but with provision to add f/6 later. The highest priorities are to maintain the best image quality and low emissivity at each site. Fusion of the first meniscus primary blank by Corning is expected in October and assembly of the second one has begun. They will be polished by REOSC near Paris who are also polishing the ESO VLT mirrors. Coast Steel in BC will build the enclosures and the award of the telescopes contract will be announced soon.

The drawing (p26) shows the final telescope design. Because the primary is on the altitude axis the upper end is light weight and presents a low cross section to the wind. The large diameter azimuthal track also provides stability against wind shake. The mirror cover is shown partly open and the walkway on which the figure is standing moves with the telescope.

In May the Gemini Board approved the instrument program proposed by the Science Committee. The program, in the table, has to fit within a very restricted budget. The responsible country is given in brackets (C=Canada). Canada is already responsible for the Adaptive Optics unit on the Mauna Kea telescope.

We have now entered a lively debate over the operations phase. If the telescopes perform as well as expected there will be a wide dynamic range in observing conditions from exquisite seeing and cool sky to mediocre seeing and high IR background. Telescope time will be very precious and scheduling will have to respond to changing conditions through the use of queues and priorities. Exposure times for certain programs become unrealistically long when conditions deteriorate beyond a certain point. The classical 2 night observing assignment will probably not happen on the Gemini telescopes except for targets of opportunity and epoch specific observations

Up to date information on the Project is available through the Gemini Newsletter of which numbers 7 and 8 came out in January and June this year. If you are not receiving a copy and would like to, contact Andy Woodsworth (woodsworth@dao.nrc.ca). Alternatively, the Tucson Project Office offers a World Wide Web home page, with an extensive project description and up-to-date announcemnts plus copies of the Newsletters. Access it by using Mosaic specifying a URL of

http://icarus.tuc.noao.edu/project/gemini.html At UBC we shall be holding a meeting `Astronomy with Large Telescopes' 31 May to 3 June 1995 for which we expect considerable international participation. A preliminary announcement has already gone out and there will be a more detailed one by the end of the year.

Gordon Walker - walker@astro.ubc.ca

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Please e-mail any suggestions/comments to Jack Penfold (jpenfold@mtroyal.ab.ca)