Lots of excitement recently regarding an editorial in the New England Journal of Medicine about data sharing. Concern was expressed that “people who had nothing to do with the design and execution of the study” would “use another group’s data for their own ends, possibly stealing from the research productivity planned by the data gatherers, or even…to try to disprove what the original investigators had posited.” The authors of the editorial stated that some researchers would characterize the people described above as”research parasites”. Needless to say, this got some people mad. Of course there was a hashtag #researchparasites, and there were some interesting blog posts, by Christie Bahlai, Derek Lowe, and Leonid Schneider. A follow-up editorial supported data-sharing in clinical trials and pushed back against the name-calling.
The whole business is bemusing from the point of view of an astronomer, since our field has a different relationship with research data compared to biomedical research. Ours is an observational science, and there’s only one sky, which everybody with the right equipment and location can see. Some astronomical objects change with time, meaning that every observation is potentially unique and irreplacable. Resources are limited, so it’s not always feasible to repeat an observation, and of course, it’s also pretty difficult to make money from astronomical observations. Research data in astronomy has a long history, starting with ancient records of unaided-eye observations, through those ancient Greeks and the maddening magnitude system, to photographic plates and DAT tapes, continuing to today’s multi-terabtye digital databases.
I don’t know the history well enough to give a full overview; rather, I want to talk about how astronomers think about sharing observational data in the present day. This is based on my own experience as someone who mostly studies nearby galaxies. In general, people in this field are not super-secretive about our data: we are mostly studying objects that are already known, rather than discovering new ones as might be the case with very distant galaxies or extrasolar planets.
In a lot of cases, astronomers in general don’t get much choice about sharing data. Most publicly-funded observatories, including space telescopes run by NASA or ESA, ground-based telescopes run as national facilities (CFHT, ESO, CTIO, and many others) now maintain archives of all their observations. Often the authors of the proposal to obtain the observations have exclusive access to the data for one to two years, the idea being that since they went to the effort of preparing the proposal, they should get a head start on the analysis. At private observatories, data tend to be a little more, well, private. I don’t think this is all big-telescope selfishness; in fact it’s likely more a question of resources. Running a telescope archive takes computers and programmers and scientists, and many observatories run on shoestring budgets. Interestingly, the private Keck Observatory does have an archive, funded by NASA. Archives can account for a substantial fraction of the research done with a telescope, from 12% for Keck, to close to half for Hubble.
Telescope archives usually contain raw data and some version of processed data. It’s not uncommon to reprocess data from an instrument multiple times, as understanding of its behaviour improves; I think some of the Spitzer archive was reprocessed half a dozen times. The level of data that you get from a telescope archive is sometimes sufficient to perform science with immediately, and sometimes not – it depends to some extent on how well-funded the archive and any associated data pipelines are.
It’s also common for public observatories to run “treasury” or “legacy” programs, often using large amounts of telescope time: the groups that propose these programs usually have to promise to make available the processed data that they generate. The key idea here is that since taxpayers of various nations paid for the facilities that obtained the data, everyone should have access to them. (In principle, observatories could just make the data available in their own countries, but that rarely happens). Some examples include NOAO Surveys, Gemini Large and Long Programs and Chandra “X-ray Visionary Projects” (!). The data released as part of these projects usually is science-ready; the teams that proposed the project usually use the data to do some of their science, and in the process get it ready to release. The Sloan Digital Sky Survey, which I believe is the most productive ground-based telescope ever, is another example of a Big Project with Lots of Public Data.
If you are an astronomer not part of a big project, you can just post data on your own website, and some people do that. Of course, people move and web servers die, so this may not be the best way to preserve data for posterity. There are places where astronomers can deposit processed data for use by others: the NASA/IPAC Extragalactic Database (NED), I-don’t-know-what-it-stands-for SIMBAD, some telescope archives (e.g., the DUSTiNGS project at IRSA), and generic data-sharing sites like figshare or even GitHub. There’s a good comprehensive list here – thanks NMSU library!
Once this data is out there, how do astronomers find it? Stay tuned for Part 2: The Virtual Observatory..