Astronomers can now freely swap time on the Gemini telecopes (pictured) and Japan's Subaru telecope. Credit: Gemini Observatory/AURA

Following a landmark agreement to swap telescope time, Japanese astronomers will gain access to the southern skies, while astronomers with the Gemini consortium will get to use specialized instruments on Japan’s premier telescope.

On 19 October, the directors of Subaru, Japan’s 8.2-metre telescope at the summit of Mauna Kea in Hawaii, and Gemini, twin 8.1-metre telescopes in Hawaii and Chile, signed an open-ended agreement that vastly increases the available time for sharing. Beginning in the spring of 2013, Gemini and Subaru astronomers can apply for time on each other’s telescopes without limits, and the amount of time swapped during each semester will be determined by demand. In theory, says Gemini director Markus Kissler-Patig, the telescopes could swap all of their time — in contrast to past arrangements, in which just a handful of nights were exchanged.

The agreement will give Japanese astronomers access to astrophysical objects in the southern skies above Chile, as well as the use of forthcoming Gemini instruments designed for studying extrasolar planets. And Gemini users from the United States, Canada, Brazil, Argentina, Australia and Chile will get to use Subaru’s new wide-field camera (see ‘Cameras to focus on dark energy’).

Ground shift

Although each observatory had an incentive to make the deal happen, it speaks to a broader shift taking place at large ground-based astronomical facilities: towards collaboration rather than competition. Previously, many large observatories had developed a full suite of basic instruments to take on their rivals on every astronomical front — even though those instruments often sat idle because only one could be used at a time.

Now, as instruments become more expensive, and the competitive frontier shifts to a new generation of 30-metre-class telescopes, the 8-metre-class observatories are starting to specialize and swap time. “It’s imprudent to build every instrument for every occasion,” says astronomer Todd Boroson, former director of the US National Optical Astronomy Observatory in Tucson, Arizona. “It’s a waste of resources to have nine instruments sitting in cabinets.”

Kissler-Patig says that he is working towards a day when the telescopes on top of Mauna Kea work more as a system. He says that the Hawaii site could end up more like the European Southern Observatory’s Very Large Telescope, which is a system of four identical 8-metre telescopes in Chile. “There’s a good chance that we integrate the entire mountain,” he says.

Taft Armandroff, director of the twin 10-metre Keck telescopes in Hawaii, says that he is open to more time swaps in the future, but that the extent of them will probably be more limited than those proposed in the Subaru–Gemini agreement. Keck has an existing agreement to swap about six nights per semester with Subaru, he says, while exchanges with Gemini have lapsed for the moment.

Time trading

Part of the problem is that it is a lot easier to negotiate time-sharing agreements between public facilities such as Subaru and Gemini than it is between public facilities and private ones, such as Keck, which is owned by universities in California. As US astronomers, Keck users can apply for time on Gemini anyway — so they have less incentive to give up time on their own telescopes.

It’s a waste of resources to have nine instruments sitting in cabinets.

That is why, for about a decade, a little-known National Science Foundation (NSF) programme provided that incentive. Called the Telescope System Instrumentation Program (TSIP), it gave money to private observatories so that they could build new instruments. In return, the observatories gave a specified number of nights on those telescopes that would be available to US astronomers at large. The programme was cancelled in 2012.

But a review of the NSF’s astronomy programme in August this year recommended that something like the TSIP programme be resurrected — although the earliest that it could be funded would be in 2014. Daniel Eisenstein, an astronomer at Harvard University in Cambridge, Massachusetts, who chaired the review, says that he would like to see the TSIP programme survive in some form. “Trading time in some manner is an essential aspect of the field going forward.”