ISO Archives Available to Scientists
27 February 1999
Researchers who feel they have an astronomical scoop based on data from the European infrared space telescope, ISO, must now work against the clock. They risk being overtaken by other groups, especially now that the ISO Data Archive, a goldmine of discoveries filled with nearly 30000 scientific ISO observations, is open and easily accessible to scientists all over the world. The ISO Data Archive received more than 2000 queries during its first month of existence.Astronomers who get observing time with a telescope can keep their data private for typically about a year after the observations, but when that time is up these data become public: all scientists can use them for their own research. That is the reason why the 600 principal investigators (instrument team leaders) who observed with ISO are in a hurry.
Many ISO data are already available to the scientific community and more are released every day. They can be accessed for free via the Internet from the ISO Archive at the ISO Data Centre (Villafranca, Spain), which opened on 9 December.
"There are still many astronomical surprises left in the ISO Archive", says ISO Project Scientist, Martin Kessler. "When an astronomer gets the data from his own observation he only has one piece of the puzzle, but the scientific community can now play with all the 30 000 pieces. You can't foresee the picture that will come out!."
One of ISO's greatest results so far has been the discovery of huge amounts of water vapour in many parts of the Universe, from the planets in the Solar System to the huge water-producing factories in the Orion and Sagittarius nebulae, or even in distant galaxies. And the detailed infrared observations are also changing the astronomers' minds about the history of the Universe: ISO is showing that the Universe was much more violent when it was about a third of its present age than previously thought, with three to four times more stars being formed.
Scientists are looking forward to more results in these and many others fields. They expect, in particular, precise news about the chemical constituents of the planets in the Solar System, namely Mars.
Easy and quick
The archive has been developed to be quick and easy to use, both for non-specialists and for highly experienced users. Its software allows the data to be delivered within hours or even less, depending on Internet traffic and extent of the user's request. The query is made through a friendly interface, and can be specifically tailored to the user's needs.
These qualities are enhanced by the fact that the archive is based on Java software, a pioneering choice considered by many too risky at the beginning but that now proves correct. The ISO archive is one of the first science databases in the world working with a fully Java-based user interface.
Thanks to the Java software, for instance, the user can see the observations in thumbnail icons before choosing them, a facility that saves time and avoids incorrect choices.
As Archive Scientist Timo Prusti comments, "There are many options to enter the query. You can use the coordinates of the object, the name, the date of the observations... And once the selection is made you can choose at which level of processing you want the products: raw data, basic science or fully processed. It's also possible to download specific software to refine the processing".
The interface also shows which data are not yet public, but specifies when they will become so. So far about 25 per cent of ISO data have become public, and the rate increases every day. Within the following months all data will become public.
The 'backstage' of the ISO Data Archive is impressive. The observations are kept in 700 CD-ROMs, and when the user make the query an automated system finds the requested data in the CDs and loads them into an ftp area.
Overall, the work of about one hundred astronomers and engineers all around the world is related to improving the ISO Archive and its running Data Centres. Apart from the ISO Data Centre at Villafranca there are six National Data Centres: in Groningen (The Netherlands); Garching and Heidelberg (Germany); Orsay-Saclay (France); Rutherford (UK); and Pasadena (California, US). The National Data Centres provide specific support to their local community.
The coordinated effort of all centres will lead to updates of processing software, closely linked to improved understanding of the calibration of the instruments.
ISO was put into orbit in November 1995, by an Ariane 44P launcher from the European space base at Kourou in French Guiana. Its operational phase lasted till 16 May 1998, almost a year longer than expected. As an unprecedented observatory for infrared astronomy, able to examine cool and hidden places in the Universe, ISO successfully made nearly 30 000 scientific observations.