For astronomers and students waiting eagerly to do science with Rubin Observatory, a milestone that brings everything one big step closer is about a week away: Data Preview 0 (DP0) will be the first in a series of three data previews leading up to the start of the Rubin Observatory Legacy Survey of Space and Time (LSST). For this data preview, participants will access simulated data using the Rubin Science Platform (RSP). Although a small number of users have been accessing the RSP on an experimental basis, this marks the first time that a wider group of science community members are invited to access the platform, and are provided with a level of service and support. The process for selecting DP0 participants aligns with Rubin's commitment to research inclusion; a diverse set of users will test this early version of the RSP in partnership with the LSST Science Collaborations.
The Rubin Observatory's Legacy Survey of Space and Time (LSST) will cover a third of the sky each night, detecting billions of stars and galaxies, and millions of transients, variables, and moving objects. The LSST represents a data set of unprecedented volume and complexity, which will be far too large for scientists to download to their personal computers for analysis. Instead, scientists will use the Rubin Science Platform (RSP), a collection of services developed by the Rubin Data Management team that allow users to process, query, visualize, and analyze the LSST data archives using next-to-the-data computing resources provided by the project, accessed through a mixture of web portal, notebook, and Virtual Observatory services.
For many astronomers, using a remote service like the RSP to leverage the massive LSST data set for their science goals may cause a change to their established workflow or require learning new skills. Enabling scientists and students to start to familiarize themselves with the RSP's software and interfaces, so that they are ready for early science when Rubin begins operations, is a primary goal of Data Preview 0.
Because the RSP is in active development, and the Rubin pre-operations team is limited in its capacity to provide user support, participation in DP0 is limited to 300 scientists and students. The DP0 participants will be supported with resources and infrastructure (e.g., tutorials, seminars, communication channels, networking opportunities), and they will be free to pursue their own science at their own pace using the data in the RSP. The number of participants will be scaled up over the course of the pre-operations period, until at least by the start of Rubin Observatory Operations all data rights holders may have RSP accounts.
Rubin Observatory received a large number of applications for the first phase of DP0. Ensuring research inclusion and participation from a diverse set of scientists and students strongly motivated the applicant selection process. An algorithm was applied to the applications pool that made selections to increase diversity in participants from underrepresented groups in astronomy (e.g., gender, race, or disability-based), from a broad range of stages in their careers, (e.g., students, researchers, or faculty), and from across the four main Rubin science pillars and beyond. In order to ensure a diverse pool of applications, there are no prerequisites for participation other than having Rubin Observatory data rights, which are available to any astronomer working in the US and Chile, and named individuals of International Contributor teams. Participants in DP0 are not required to have knowledge of python or experience with Jupyter Notebooks; scientists who have not previously had training or access to these resources are encouraged to use DP0 as an opportunity to familiarize themselves with new tools.
Because Rubin Observatory is still under construction, Data Preview 0 is using the simulated LSST-like data set generated by the LSST Dark Energy Science Collaboration (DESC) as part of DESC’s second Data Challenge (DC2). The DESC's DC2 effort was a huge initiative over several years to simulate a set of images that imitate five years of an LSST-like survey over 300 square degrees. These images are very realistic: they have the same instrumental characteristics that are expected for the Rubin Observatory's LSST Science Camera, and they were processed with an early version of the LSST Science Pipelines that will eventually be used to process LSST data.
The DC2 simulated universe includes galaxies, clusters, large scale structure, Milky Way stars (some of which vary in brightness over time, such as RR Lyrae and Cepheids), and Type Ia supernova explosions. These aspects make the DC2 simulation a practical basis for scientists learning to use the RSP during DP0, a useful data set for astronomers interested in extragalactic astrophysics, and a powerful tool for cosmological analyses. The DESC has made the DC2 data set publicly available (see this note), and more information about the DC2 simulation can be found in this paper.
There will be two stages of DP0. The first stage (DP0.1, in 2021) will make the original DESC simulated data set available to users, and in the second stage (DP0.2, in 2022), the data set will be reprocessed by the LSST science pipelines in order to produce data products that will more closely resemble those of an LSST data release. The DP0 delegates will fill an important role in both phases, testing and providing feedback as they gain experience working with LSST-like data products using the Rubin Science Platform (RSP). For the Data Previews, the RSP will be hosted at the Interim Data Facility (IDF) on the Google Cloud Platform. This agreement marks the first time a cloud-based data facility has been used for an astronomy application of this magnitude. The IDF will use Google Cloud’s Storage, Kubernetes Engine and Google Cloud Compute, which will together provide the Rubin Observatory user community with the ability to experience LSST-like data in an early version of the real analysis environment.
More information and discussion about DP0 is available on community.lsst.org (under tags, search on “dp0”), and scientists are encouraged to keep updated about Rubin data preview opportunities—and contribute to the conversation—via this community forum.
