Early Science Program

"Early science" is defined as any science enabled by Rubin for its community prior to the first annual data release, Data Release 1 (DR1), of the Legacy Survey of Space and Time (LSST).

The goal of the program is to support the community as they develop their LSST analysis software and workflows, and to enable high-impact science as soon as possible

The program includes:

• a series of Data Previews produced by reprocessing of science-grade commissioning data,
• a progressive ramp-up of the alert stream and Prompt Products availability, and
• an incremental template-generation strategy to support alert production.

This page summarizes "Rubin Observatory Plans for an Early Science Program", Rubin Tech Note 11 (RTN-011; https://doi.org/10.71929/rubin/2584021).

Data previews

A series of data releases that progressively increase in size and complexity as a ramp up to the first annual data release.

Data Preview 0 (DP0): Simulated LSST-like datasets

Available now (dp0.lsst.io). Includes simulated images and catalogs for Galactic and extragalactic objects (including variable stars and supernovae), and catalogs of moving objects.

Data Preview 1 (DP1): LSSTComCam commissioning

Available now (dp1.lsst.io). Based on images from the seven-week on-sky campaign with the LSST Commissioning Camera (LSSTComCam), 24 October 2024 to 11 December 2024. DP1 covers seven small fields with a range of stellar densities, depths, and cadences, and offers small versions of most image and catalog types to help prepare scientific analyses and workflows.

Data Preview 2 (DP2) : LSSTCam commissioning and Science Validation surveys

"Early DP2" target: Jul-Sep 2026 (dp2.lsst.io). In the early phase, deep coadded images and all catalogs will be available. Complete DP2 target: Oct-Dec 2026, when visit and difference images will become available. This phased delivery reflects a bandwidth constraint in Rubin’s hybrid cloud architecture (Section 3.3 of RTN-011). DP2 will be based on commissioning and small-field survey visits with LSSTCam obtained between April 2025 and January 2026. DP2 covers the Deep Drilling Fields (DDFs), small-field survey regions, and a contiguous region of deeply coadded images that is ~3000 square degrees. See also Section 2 and 3.3 of RTN-011 for more general information, and RTN-111 for a quantitative summary.

Resources to learn more about the history and progression of commissioning and the SV surveys:

• Science Validation survey summary (as of 30 September 2025)
• weekly technical updates about commissioning
• nightly scheduler reports

Prompt data products

Some Prompt products are available now: prompt-products.lsst.io.

Prompt data products are the result of Difference Image Analysis (DIA). They include the alerts; the visit and difference images; and catalogs of difference-image detections and their associated measurements.

Alert production and template generation

Alerts began streaming in February 2026.

Prior to DR1, the alert stream cannot run at full scale because DIA requires template images, which would typically be constructed as part of an annual data release. In order to produce alerts on a limited scale, templates are being generated from commissioning and early operations data.

Learn more about alerts and brokers.

Solar System discoveries

New solar system objects discovered by Rubin Observatory are being reported to the Minor Planet Center on an ad-hoc basis.

Prompt Products Database (PPDB)

Target: Sep-Oct 2026. The catalogs that result from Prompt processing are stored in the PPDB. These contents are very similar to the cumulative content in all released alerts.

Prompt images and direct source

Target: Oct-Dec 2026. Prompt-processed visit images and difference images will be subject to the 80-hour embargo period. As a temporary measure to support Early Science, source detection will be run on all Prompt-processed visit images and the results made available as a source catalog that accompanies the visit images on an 80-hour timescale. This temporary measure would end with the release of DR1.

See Section 4 of RTN-011 for details on the Prompt data products.

Data Release 1 (DR1)

Anticipated one year after the end of LSST start (TBD). To be based on the first year of data taken as part of the 10-year LSST survey. Processing is anticipated to take one full year, and will deliver the full suite of data products.

Questions?

Use the Support and Early Science categories in the Rubin Community Forum.