Vera C. Rubin Observatory

Rubin photographs the whole southern sky every few nights for 10 years

The Vera C. Rubin Observatory runs the Legacy Survey of Space and Time (LSST), a 10-year survey that images the whole southern sky every few nights and comes back to each point about 800 times. A new image comes every 40 seconds, about 1,000 a night, through six filters (u, g, r, i, z and y) that span 320 to 1,050 nanometers, from the ultraviolet to the near-infrared.

Supernovae, variable stars, asteroids and comets show up as changes from one visit to the next, and the stacked visits build a catalog projected at about 37 billion objects: 20 billion galaxies and 17 billion stars. In about six weeks of early optimization surveys, Rubin found more than 11,000 new asteroids, among them 33 near-Earth objects and 380 trans-Neptunian objects.

Rubin is a US government facility run jointly by NSF NOIRLab, which AURA manages, and the Department of Energy's SLAC National Accelerator Laboratory, with funding from NSF and the DOE Office of Science. The telescope is the Simonyi Survey Telescope, named for Charles and Lisa Simonyi, who gave $20 million in January 2008; Bill Gates gave $10 million. Construction cost about $680 million. Scientists at Chilean institutions get privileged access to the data.

The observatory stands on El Penon peak of Cerro Pachon in the Coquimbo Region of Chile, at 2,682 m, next to Gemini South and SOAR. Its base facility is in La Serena, about 100 km away by road. Construction was authorized in August 2014, LSSTCam saw first photons on 15 April 2025, the first-look images came out on 23 June 2025, public alerts have flowed since 24 February 2026, and NSF announced the official start of the LSST on 30 June 2026. See the Vera C. Rubin Observatory listing and more observatories in Chile.

Three mirrors on two pieces of glass fold the light into a field of 45 full moons

Light lands on the outer ring of the 8.4 m primary mirror, rises to the 3.4 m convex secondary (M2), drops back to the tertiary at the center of the primary glass, and climbs into the camera. The Richard F. Caris Mirror Lab at the University of Arizona figured the primary and tertiary on one monolithic glass, the M1M3, between 2008 and 2015. The design gives an effective aperture equal to a 6.42 m mirror, a collecting area of 35 square meters, and a field of view of 9.6 square degrees (3.5 degrees across), about 45 full moons.

M2 is the largest convex mirror in operation. Corning cast the blank from fused pieces of ULE titania-silicate glass in Canton, New York; L3Harris polished it in Rochester, New York; it reached the summit in December 2018.

Rubin coats its mirrors on the mountain. VON ARDENNE of Germany built the coating plant, with eight magnetrons, a cleaning and decoating station, and a 128-metric-ton vacuum chamber made by MAN in Deggendorf. It first coated M2 on 16 July 2019 and finished the protected-silver coating on M1M3 on 27 April 2024.

Inside the camera, Ball Aerospace built the L1 (1.57 m) and L2 (1.2 m) lenses with Arizona Optical Systems of Tucson as subcontractor; L1 is the largest lens made for astrophysics. Thales SESO in Aix-en-Provence shaped and polished the six filter substrates, Materion in Westford, Massachusetts applied their interference coatings in a chamber built for the job, and Lawrence Livermore National Laboratory ran the camera optics program and mounted the filters.

LSSTCam reads 3.2 gigapixels from 189 CCDs in about two seconds

SLAC designed, built and integrated LSSTCam: 3,010 kg, 4.49 m long, with a front lens more than 1.5 m tall. Its focal plane holds 189 science CCDs in 21 rafts of nine, plus eight wavefront sensors and eight guider sensors in four corner rafts. Each CCD reads out through 16 amplifiers, and the whole focal plane reads out in about two seconds.

Two vendors made the science CCDs, and each raft uses sensors from one of them. Teledyne e2v in the UK made one share. The Imaging Technology Laboratory (ITL) at the University of Arizona made more than 100 science sensors of 4k x 4k pixels plus the 4k x 2k wavefront sensors, to a design by Semiconductor Technology Associates (STA) of California, and supplied every sensor in LSSTComCam, the commissioning camera. Brookhaven National Laboratory built and tested the 21 science rafts and shipped them to SLAC.

Cryogenics: the sensors run at minus 148 F in a vacuum

The focal plane sits in a vacuum cryostat at minus 148 F (minus 100 C), which suppresses thermal noise in the silicon.

Filters and shutter: a swap in about two minutes

IN2P3/CNRS, through five French laboratories, built the filter exchange system: carousel, auto-changer and loader. It holds five of the six filters at once and moves each 75 cm, 40 kg filter into place to a tenth of a millimeter, in about two minutes. The shutter opens or closes in about one second.

A Spanish-built mount of 460 metric tons turns the telescope full circle in 36 seconds

A new image every 40 seconds needs a fast mount. The telescope mount assembly is a 460-metric-ton steel structure 10 m across that turns a full rotation in 36 seconds. GHESA of Spain led the turnkey consortium, from design to commissioning, with Asturfeito, which fabricated the structure and assembled and validated it in Asturias. Tekniker wrote the mount control system and the trajectory software for the camera rotator, and Empresarios Agrupados supported assembly and testing at Cerro Pachon. Phase of Italy, SKF of Sweden and Heidenhain of Germany are named members of the mount team; the source does not say which parts each supplied.

CAID Industries in Tucson built and vacuum tested the 26,000 kg steel cell that holds M1M3. European Industrial Engineering (EIE) of Italy built the 30 m rotating dome and shipped its azimuth rail, bogies and ring beam from Italy; Galbiati Group in Lecco made the 15 bogie wheel assemblies, 14 in use and one spare. Besalco of Chile built the summit facility.

About 10 terabytes a night travel by fiber from Cerro Pachon to SLAC in California

LSSTCam produces about 10 TB a night, carried by fiber to a custom data acquisition system. From the summit the data go down to the base facility in La Serena, across Chile on REUNA, the national research and education network, to Santiago, then on redundant routes to Miami over AmLight, run by Florida International University and active since March 2018. The link needs at least 100 Gbit/s. RNP, the research network of Brazil, is a named network partner.

The data land at the Rubin US Data Facility (USDF) at SLAC, which runs prompt processing and processed all of Data Preview 1. The Rubin Science Platform, where scientists query and analyze the data, runs on Google Cloud, which hosted the Interim Data Facility from 2020; faster transfer from SLAC to Google Cloud is the USDF's priority upgrade. Future data releases will be processed across three sites: the USDF, the French Data Facility (FrDF) run by IN2P3/CNRS, and the UK Data Facility (UKDF) run by LSST:UK. Over 10 years the survey is projected to produce a 500 PB set of images and data products.

Alert Production issues an alert within 60 seconds for each change it finds, up to 7 million a night by NSF's count; the first wave was about 800,000. Seven full-stream brokers take the whole stream: ALeRCE, AMPEL, ANTARES, Babamul, Fink, Lasair and Pitt-Google. SNAPS and POI Broker work downstream of them.

Data Preview 1 (DP1) held 1,792 LSSTComCam exposures from 48 nights between 24 October and 11 December 2024: about 3.5 TB and 2.3 million objects, processed in 17,024 CPU hours. Data Preview 2 (DP2) covers about 30,000 LSSTCam science visits, about 1% of the LSST. Data Release 1, about 10% of the survey, is planned two years after the survey start.

A neural network trained on citizen-science labels screens every Rubin alert

The Alert Production pipeline scores each candidate with a Real/Bogus reliability model: a three-layer convolutional neural network in PyTorch that reads 51 x 51 pixel cutouts of the template, the science image and their difference, and returns a score from 0 to 1. Version 0.1 went into service in September 2025 and was used for DP1. Version 0.2, deployed on 18 February 2026 for the public alerts, was trained on 13,178 sources labeled by volunteers in Rubin Difference Detectives, a Zooniverse project. Version 0.3, deployed on 9 July 2026 for DP2, uses a reliability cutoff of 0.5.

The brokers then run their own machine-learning classifiers to filter the stream for research teams; ALeRCE, for one, classifies alerts by type.

Rubin takes public visitors by reservation through NOIRLab, and the spaces fill quickly

Public visits to Rubin are booked through the NOIRLab Visit Cerro Pachon reservation page, and spaces fill quickly. Rubin's own schedule, price and age rules are set on that booking page; check it before planning a trip.

The NOIRLab tours of Gemini South and SOAR on the same mountain are free and leave Fridays at 9:00 am from the Observatory Access Gate (Route 41/D-317, km 50, from La Serena), for groups of four to 25, with no children under six.

Sources

1. NSF: Vera C. Rubin Observatory begins the Legacy Survey of Space and Time
2. SLAC: the LSST Camera
3. Wikipedia: Vera C. Rubin Observatory
4. Rubin Observatory: LSSTCam documentation
5. Rubin Observatory: the secondary mirror
6. Rubin Observatory: About
7. Rubin Observatory: About
8. NSF NOIRLab: visits to Cerro Pachon
9. arXiv: Rubin Data Preview 1
10. AmLight: Rubin Observatory status (R. Blum, 2026)
11. GeekWire: Rubin Observatory starts its alert stream
12. Google Cloud: Rubin Observatory partners with Google Cloud
13. Rubin Observatory: alerts and brokers
14. Rubin Observatory technical note DMTN-337: the Real/Bogus model
15. SLAC: Rubin finishes the reflective coating of its main mirror
16. Corning: Rubin Observatory and the secondary mirror blank
17. VON ARDENNE: coating technology on the summit
18. Rubin Observatory: M1M3 mirror cell contract with CAID Industries
19. Tekniker: the Rubin Observatory telescope mount
20. Rubin Observatory: dome working details
21. The Engineer: Teledyne e2v sensors for the camera
22. University of Arizona ITL: LSST sensor contracts completed
23. Brookhaven National Laboratory: LSST CCDs and rafts
24. Ball Aerospace delivers the lens assembly to LLNL
25. LLNL wraps development of optical components for Rubin
26. Rubin Observatory: the filter exchange system