Sir

Recent budgetary choices have forced the closure of the US National Radio Astronomy Observatory 12-m telescope in Kitt Peak, Arizona. As this detrimentally affects astronomy in many ways, I am writing to oppose this move.

The 12-m telescope remains one of the most important and vital components of US millimetre astronomy. For graduate students in the United States, it is the only accessible, competitive, peer-reviewed facility capable of both training them as future scientists and providing for internationally recognized research. The 12-m telescope is a vital component to my own PhD thesis and much of my future work is predicated on its existence. Specifically, wide-field mapping and full synthesis imaging will not be possible without it.

Alternatives such as CSO, JCMT, HHT and IRAM are inadequate. None of them except IRAM 30-m has the frequency coverage of the 12-m. For example, deuterium-bearing molecules are often found to have ground-state transitions below 85 GHz, the limiting tuning range of many other receiver systems. The deuterium component of the insterstellar medium (ISM) — as a measure of primordial nucleosynthetic products, chemical evolution in the ISM, and observational limit on abundance predictions from star-formation theories — will no longer be accessible.

The alternative facilities noted above are less accessible to US astronomers than the 12-m telescope, either because the observatories have closed associations with their parent institutions or because they are very expensive to reach. Furthermore, the HHT, though a capable enough system, lacks receivers at 2-mm and 3-mm wavelengths to compensate for the loss of the 12-m telescope.

Two solutions are apparent. The first is to establish a consortium of universities to take over operation of the 12-m. Some emergency funding, even if outside the National Science Foundation's budget, must be obtained in the interim period in order to allow minimal operation of the 12-m. This will also allow NRAO to retain the staff, engineers and scientists whose vast millimetre knowledge will disappear if the closure goes through as planned.

Many of us have written to counteract the impression that the 12-m telescope is no longer a vibrant instrument, or that NRAO has overextended itself. The national observatories maintain widely accessible, strong facilities with flexibility and extensibility. The 12-m telescope remains important until work begins of the construction of the Atacama Large Millimetre Array (ALMA) — 64 antennas located at 5,000 m in Chile's Atacama Desert.