Vera C. Rubin Observatory’s LSST: The 10-Year Sky Survey Starting Now

After more than a decade of construction and commissioning, the Vera C. Rubin Observatory on Cerro Pachón in Chile is poised to begin its landmark Legacy Survey of Space and Time (LSST). As of the American Astronomical Society meeting in June 2026, the observatory is reported to be "days to weeks away" from starting the 10-year survey . Here is everything you need to know about the LSST — its scientific goals, its unprecedented camera, its observing strategy, the milestones already reached, and how researchers around the world can access its firehose of data.

The Four Core Science Goals of the LSST

The LSST was designed from the ground up to answer four overarching scientific questions, each demanding a panoramic, time-resolved view of the entire southern sky .

Probing Dark Energy and Dark Matter

A primary goal is constraining the nature of dark energy through weak gravitational lensing (cosmic shear) and measurements of large-scale structure across cosmic time . After one year of data, LSST's dark-energy constraints are expected to match the precision of the Dark Energy Spectroscopic Instrument (DESI), offering an independent test of hints that dark energy may be evolving . The survey will also map the distribution of dark matter by measuring how its gravity warps the light of distant galaxies.

Inventory of the Solar System

The LSST is expected to discover and catalog more than 5 million asteroids, including about 100,000 near-Earth objects . By repeatedly scanning the same fields, the survey will track moving objects across the entire southern sky, providing an unprecedented census of small bodies in our solar system.

Exploring the Transient Optical Sky

The survey will detect millions of supernovae, variable stars, and other transient events. Within 60 seconds of detection, a real-time alert stream will be issued to the global astronomical community . In a single night of early operations in February 2026, the Rubin alert system captured 800,000 transient alerts .

Mapping the Milky Way

A deep, multicolor census of stars in our own galaxy will reveal the structure, formation history, and stellar populations of the Milky Way in extraordinary detail, cataloging an estimated 20 billion stars .

Key Capabilities: The Telescope, Camera, and Data Pipeline

The World's Largest Digital Camera

The heart of the LSST is LSSTCam, a 3.2-gigapixel camera — the largest digital camera ever built for astronomy . It is paired with an 8.4-meter telescope that has an exceptionally wide 3.5-degree field of view, allowing it to cover a huge area of sky in a single exposure .

Survey Cadence

Over 10 years, the survey will image the entire visible southern sky — approximately 18,000 square degrees — in six optical and near-infrared filters (u, g, r, i, z, y) . The baseline observing strategy is called "Wide Fast Deep" (WFD), which obtains a roughly 30-second exposure of each patch of sky every three nights . The primary survey uses less than 3% of observing time for dedicated programs like following up small solar system bodies at extreme distances .

Data Volume and Depth

The survey will be the largest astronomical dataset ever produced: about 60 PB of raw data, with an estimated 40 billion stars, galaxies, and asteroids cataloged and 30 trillion total individual observations . The coadded images — produced by stacking hundreds of individual visits — will reach magnitude r~27.5 (36 nJy), deep enough to detect galaxies far beyond redshift 1 .

Operational Plan and Observing Strategy

• Duration and cadence: The LSST will run for 10 years, imaging the visible sky roughly twice each week . The observatory takes about 500 pointings per night, each covering 10 square degrees, for roughly 1,000 unique pointings over the entire survey area every three to five nights .
• Additional modes: Beyond the main WFD survey, there are deep-drilling fields — small sky regions observed repeatedly in rapid succession — and a special program designed to detect and track supernovae and other fast-evolving transients .
• Operations handover: The observatory reached substantial construction completion and formally transitioned to the operations phase on October 25, 2025 . The telescope was back on sky the very next day for early science operations .

Major Milestones: Past, Present, and Near Future

Milestone	Date / Status	Source
Early commissioning with engineering camera (LSSTComCam)	Late 2024, first pixel obtained October 2024
LSSTCam commissioning begins	April 2025
"First Look" data released to public	June 23, 2025
Construction-to-operations handover	October 25, 2025
Rubin real-time alert system goes live (800K alerts/night)	February 24, 2026
LSST survey start	Days to weeks away as of late June 2026
Data Preview 2 (DP2) — first LSSTCam science-grade data	Expected mid-2026 (target Jul–Sep 2026); official release Oct–Dec 2026
First annual Data Release (DR1)	Expected ~late 2026 to early 2027 (based on earlier 6-month plan); later updated to be based on one year of data, with some estimates pointing to ~June 2028

Note on the start date: The start of the LSST has slipped multiple times, with early predictions pointing to late 2025, then early 2026. An April 2026 community update reported good progress but noted the team was still working to improve image quality and system performance . As of June 17, 2026, the survey was described as "days to weeks away" . The LSST community forum includes a post titled "The LSST has started!" dated June 30, 2026, suggesting the survey may have begun within that window .

Data Accessibility: Who Can Access What, and How

LSST data are processed, calibrated, and delivered as science-ready images, catalogs, and real-time alerts through automated pipelines — no manual reduction is needed to do science .

Tiers of Data Access

• Public data products: Alert packets and the Prompt Products Database (including light curves and moving-object detections) are public immediately — anyone in the world can access them .
• Proprietary data products: Prompt processed images and the annual Data Release products have a two-year proprietary period, during which only Rubin data rights holders can access them . After two years, they become public, though non-rights-holders cannot use Rubin's Data Access Centers for download .

Four Main Access Methods

1. Rubin Science Platform (RSP): The primary access point for data rights holders — accounts are available to scientists at U.S., Chilean, and partner institutions. The RSP provides computational resources for analysis without needing to download data .
2. Alert Brokers: Third-party services (community-based software systems) that receive and distribute the real-time alert stream .
3. Minor Planet Center: The central clearinghouse for solar system object detections .
4. Independent Data Access Centers (IDACs): Hosted at partner institutions, these provide additional computational and storage resources for affiliated scientists .

What is Available Now

• DP0 and DP1: Data Previews 0 (simulated data) and 1 (commissioning camera data) are already released to the scientific community for pipeline development and early science .
• DP2: The first LSSTCam-based, science-grade data preview is scheduled for mid-to-late 2026 .
• DR1: The first annual Data Release will include deep coadded images, single-visit images, source catalogs, forced-source photometry, and light curves — expected within about a year of the survey start, though some projections extend to June 2028 .

Key Caveat: The Start Date is Fluid

Commissioning the world's largest digital camera to the stringent image-quality standards needed for precision cosmology is a complex engineering challenge. The exact start date for the LSST has been pushed back multiple times. As of this writing, the best estimate is that the survey will begin within days to weeks, with official confirmation expected imminently. Researchers and the public should monitor the Rubin Observatory community forum and official announcements for the exact start date .