Vera C. Rubin Observatory

The base facility is located about 100 km away from the observatory by road, in La Serena. The observatory is named for Vera Rubin, an American astronomer who pioneered discoveries about galactic rotation rates. It is a joint initiative of the U.S. National Science Foundation (NSF) and the U.S. Department of Energy's (DOE) Office of Science and is operated jointly by NSF NOIRLab and SLAC National Accelerator Laboratory. The Rubin Observatory houses the Simonyi Survey Telescope, a wide-field reflecting telescope with an 8.4-meter primary mirror. It uses a variant of three-mirror anastigmat to deliver sharp images over a 3.5-degree-diameter field of view. Images are recorded by a 3.2-gigapixel charge-coupled device imaging (CCD) camera, the largest camera yet constructed. Rubin saw first light in June 2025 and started full survey operations in July 2026, taking an image of the night sky every 40 seconds in order to complete a full scan of the southern sky every few days for the next ten years. The observatory is expected to catalog millions of supernovae, more than five million asteroids (including ~100,000 near-Earth objects), and image approximately 17 billion stars and 20 billion galaxies.

• Angular Resolution — 0.7 median seeing limit 0.2 pixel size • Code — X05 • Website — https: rubinobservatory.org/

• Illustration — Vera C. Rubin Observatory and the Milky Way Galaxy • Illustration — Vera C. Rubin Observatory on Cerro Pachón mountain in Central Chile The telescope was originally named the Large Synoptic Survey Telescope, where the word synoptic—derived from the Greek words σύν (syn 'together') and ὄψις (opsis 'view')—describes observations that give a broad view of a subject. In June 2019, the observatory was renamed the Vera C. Rubin Observatory as proposed by United States Representative Eddie Bernice Johnson and Resident Commissioner of Puerto Rico Jenniffer González-Colón. The renaming was enacted as United States law on 20 December 2019, and announced at the 2020 American Astronomical Society winter meeting. The name honors Rubin and her colleagues' probes of the nature of dark matter by mapping and cataloging billions of galaxies through space and time. The telescope itself is named the Simonyi Survey Telescope, in recognition of private donors Charles and Lisa Simonyi. The LSST acronym was repurposed to refer to the survey that the observatory will perform as the "Legacy Survey of Space and Time", with the camera as the "LSST Camera".

The Rubin Observatory was proposed in 2001 as the LSST. Construction of the mirror began in 2007 with private funds. The LSST then became the top-ranked large ground-based project in the 2010 Astrophysics Decadal Survey, and officially began construction on 1 August 2014. Funding came from the NSF, DOE, and private funding raised by the private LSST Discovery Alliance. Operations are managed by the Association of Universities for Research in Astronomy (AURA). Construction cost was expected to be about $680 million. Site construction began in April 2015. The first pixel with the engineering camera came in October 2024, while system first light images were released 23 June 2025. Full survey operations began on 30 June 2026, having been delayed by COVID-related issues. The Rubin Observatory is the successor to a tradition of sky surveys. These started as visually-compiled catalogs in the 18th century, such as the Messier catalog. This was replaced by photographic surveys, starting with the 1885 Harvard Plate Collection, the National Geographic Society – Palomar Observatory Sky Survey, and others. By about 2000, the first digital surveys, such as the Sloan Digital Sky Survey (SDSS), began to replace the earlier photographic plate surveys. The Rubin Observatory evolved from the Dark Matter Telescope, mentioned as early as 1996. The fifth decadal report, Astronomy and Astrophysics in the New Millennium, was released in 2001, and recommended the "Large-Aperture Synoptic Survey Telescope" as a major initiative. Even at this early stage the basic design and objectives were set: The Large-aperture Synoptic Survey Telescope (LSST) is a 6.5-m-class optical telescope designed to survey the visible sky every week down to a much fainter level than that reached by existing surveys. It will catalog 90 percent of the near-Earth objects larger than 300 m and assess the threat they pose to life on Earth. It will find some 10,000 primitive objects in the Kuiper Belt, which contains a fossil record of the formation of the solar system. It will also contribute to the study of the structure of the universe by observing thousands of supernovae, both nearby and at large redshift, and by measuring the distribution of dark matter through gravitational lensing. All the data will be available through the National Virtual Observatory, providing access for astronomers and the public to very deep images of the changing night sky. Early development was funded by small grants, with major contributions in January 2008 by software billionaires Charles and Lisa Simonyi and Bill Gates, of $20 million and $10 million, respectively. $7.5 million was included in the U.S. President's FY2013 NSF budget request. DOE funded the digital camera component built by the SLAC National Accelerator Laboratory, as part of its mission to understand dark energy. NSF funding for the rest of construction was authorized on 1 August 2014. The lead organizations are: • The SLAC National Accelerator Laboratory to design and construct the LSST camera • The National Optical Astronomy Observatory to provide the telescope and site team • The National Center for Supercomputing Applications to construct and test the archive and data access center • The Association of Universities for Research in Astronomy to oversee construction In May 2018, the United States appropriated more funding for the telescope than had been requested, to speed construction and operation. Telescope management was unsure this would help, since at that stage of construction they were not cash-limited. • Illustration — First released image: the Trifid and Lagoon nebulae • Illustration — Virgo Cluster taken by Vera C. Rubin Observatory The first photons resolved by the complete instrument were detected on 15 April 2025, appearing as rings before the instrument was adjusted to focus them as dots. Images from the first light of the full telescope and camera combination were released on 23 June 2025. The first teasers were a composite image of the Trifid and Lagoon nebulae and extracts from a wide-field view of galaxies in the Virgo Cluster. The image of the Virgo Cluster was taken in early May over four nights. The early images showed over 2,000 new asteroids. Watch parties for the release were held across six continents as people from 28 countries had been involved. An early discovery was the unusually large and quickly rotating asteroid in the Main Belt.

The Simonyi Survey Telescope design is unique among large telescopes (8-meter-class primary mirrors) for its wide field of view: in diameter, or. For comparison, both the Sun and the Moon, as seen from Earth, are about in apparent diameter and each covers an apparent area of about. Combined with its large aperture (and thus light-collecting ability), this gives Rubin a large etendue of 319 m 2 ⋅deg 2. This is more than three times the etendue of other large-entendue telescopes, the Subaru Telescope with its Hyper Suprime Camera and Pan-STARRS, and more than an order of magnitude larger than most large telescopes.

• Illustration — Optics The earliest reflecting telescopes used spherical mirrors that were easy to fabricate and test. However, because they suffer from spherical aberration; a long focal length was needed to achieve a tolerable level of spherical aberration. Making the primary mirror parabolic removes spherical aberration on-axis, but the field of view is then limited by off-axis coma. Such a parabolic primary, with either a prime or Cassegrain focus, was the most common optical design up through the Hale Telescope in 1949. After that, telescopes mostly used the Ritchey–Chrétien design, using two hyperbolic mirrors to remove both spherical aberration and coma, increasing the useful field of view, limited by astigmatism and higher-order aberrations. Most later large telescopes used this design—for example, the Hubble and Keck telescopes. LSST instead uses a three-mirror anastigmat to cancel astigmatism by employing three non-spherical mirrors. The result is sharp images over a wide field of view, at the expense of some light-gathering power due to the large tertiary mirror obscuring part of the optical path. The telescope's primary mirror (M1) is 8.4 m in diameter, the secondary mirror (M2) is 3.4 m in diameter, and the tertiary mirror (M3), inside the ring-like primary, is 5.0 m in diameter. The secondary mirror is the largest convex mirror in any operating telescope. (It will be surpassed by the Extremely Large Telescope's 4.2-meter secondary when complete). The second and third mirrors reduce the primary mirror's light-collecting area to 35 m2, with an effective aperture equivalent to a 6.42 m diameter single mirror. Multiplying the collecting area by the field of view produces an étendue of 336 m 2 ⋅deg 2; the actual figure is reduced by vignetting. The primary and tertiary mirrors (M1 and M3) are formed from a single piece of glass, the M1M3 monolith. Placing the two mirrors in the same location minimizes the overall length of the telescope, making it easier to quickly reorient. Making them from the same piece of glass results in a stiffer structure than two separate mirrors, contributing to rapid settling after motion. • Illustration — L1 lens, 2018 The optics includes three corrector lenses to reduce aberrations. These lenses, and the telescope's filters, are built into the camera assembly. The first lens, at 1.55 m in diameter, is the largest non-compound lens ever built, and the third lens forms the vacuum window in front of the focal plane. Unlike many telescopes, Rubin does not attempt to compensate for atmospheric dispersion. Such correction, which requires adjusting an additional element in the optical train, would be difficult to achieve in the 5 seconds available between pointings. It is also a technical challenge due to the short focal length. As a result, shorter wavelength bands away from the zenith have reduced image quality. • Illustration — Diagram of the Active Optics sensors

The telescope uses an active optics system, with wavefront sensors at the corners of the camera, to keep the mirrors accurately figured and in focus. The field of view is too large to use adaptive optics to correct for atmospheric seeing. Sensing occurs in three stages: • Laser trackers make sure the components are centered and are close to the intended positions. • Open-loop corrections are applied to correct for intrinsic mirror aberrations, component sag as a function of elevation and temperature, and filter selection. • Focus and figure measurements are made by sensors at the corners of the field of view to correct the optics. The precise shape and focus of the mirror assembly is estimated, and then corrected, by comparing the images on four sets of deliberately defocused CCDs (one in front of the focal plane and one behind, see figure). One correction method proceeds analytically, estimating a Zernike polynomial description of the current shape of the mirror, and from this computing a set of corrections to restore figure and focus. Another method, considerably faster, uses machine learning for this task. • Illustration — Camera sensor

• Illustration — Life-size model of the focal plane array – the array's diameter is 64 cm, and will provide 3.2 gigapixels per image. The image of the Moon (30 arcminutes) is present to show the scale of the field of view. The model is held by Suzanne Jacoby, the Rubin Observatory communications director. The 3.2-gigapixel digital camera takes 30-second exposures. The camera is at the tertiary focus, not the prime focus. Located at a "trapped focus" in front of the primary mirror, the associated technical problems are similar to those of a conventional prime-focus survey camera. Repointing such a large telescope (including settling time) within 5 seconds requires a short and stiff structure. This in turn implies a small f-number, which requires precise focusing. Using two 15-second exposures is a compromise to allow spotting both faint and moving sources. The single 30-second exposure recommendation reduces the overhead of camera readout and telescope re-positioning, allowing deeper imaging. Cosmic ray hits on the CCDs ultimately became detected reliably in a single 30-second image. The camera focal plane is flat and 64 cm in diameter. The main imaging is performed by a mosaic of 189 16-megapixel CCD detectors. They are grouped into a 5×5 grid of "rafts". The central 21 rafts contain 3×3 imaging sensors, while the four corner rafts contain three each, for guiding and focus control. The CCDs provide better than 0.2-arcsecond sampling, and are cooled to approximately −100 C to reduce noise. The camera includes a filter located between the second and third lenses, and an automatic filter-changing mechanism. Although the camera has six filters (ugrizy) covering 330–1080 nm wavelengths, the camera's position between the secondary and tertiary mirrors limits the size of its filter changer. It can hold five filters at a time, so one of the six is omitted each night.

• Illustration — Comparison of primary mirrors of several optical telescopes – the Rubin Observatory, in green, with its very large central hole, is near the center of the diagram. The Observatory will image about of the southern sky with six filters in its main survey, with about 825 visits to each spot over 10 years. The 5σ (SNR greater than 5) magnitude limits are expected to be r 2, respectively). The basic design is conventional: an altitude over azimuth mount made of steel, with hydrostatic bearings on both axes, mounted on a pier that is isolated from the dome foundations. The Observatory pier is unusually large (16 m diameter), robust (1.25-meter-thick walls) and mounted directly to virgin bedrock, where care was taken during site excavation to avoid using explosives that would crack it. Other unusual design features are linear motors on the main axes and a recessed floor on the mount. This allows the telescope to extend slightly below the azimuth bearings, lowering its center of gravity. The contract for the assembly was signed in August 2014. It passed its acceptance tests in 2018 and arrived at the site in September 2019. By April 2023, the mount was declared "essentially complete" and turned over to the Observatory.

In August 2015, the LSST Camera project, separately funded by the U.S. Department of Energy (DoE), passed its "critical decision 3" design review. On 31 August, construction began at SLAC. By September 2018, the cryostat was complete, the lenses ground, and 12 of the 21 CCD rafts had been delivered. As of September 2020, the entire focal plane was undergoing testing. By October 2021, the last of the six filters had been finished and delivered. By November 2021, the entire camera had been cooled to its required operating temperature, allowing final testing. • Illustration — Rendering of the Rubin Observatory camera • Illustration — Color-coded cutaway drawing of the Rubin Observatory camera • Illustration — Exploded view of the optical components of the Rubin Observatory camera • Illustration — Vera C. Rubin Observatory Commissioning Camera install Before the final camera installation, a smaller and simpler version (the Commissioning Camera, or ComCam) was used "to perform early telescope alignment and commissioning tasks, complete engineering first light, and possibly produce early usable science data". The camera was reported complete in early 2024. The camera arrived at the observatory in May 2024, and was installed in March 2025.

The data must be transported from the camera at the summit, to the base facilities, and then to the Rubin Observatory United States Data Facility (USDF) at SLAC. Data is routed via a $5 million dedicated encrypted network to a United States Intelligence Community facility in California. An automated system detects events, filters events containing sensitive objects, and releases imagery covering the remaining events to the scientific community after one minute. Complete images are released 80 hours later, after the satellites' orbits change, avoiding the permanent redaction done to images from the Pan-STARRS survey. This transfer must be 100 Gbit/s or better and reliable, since the USDF is where the data is processed into scientific data products, including real-time alerts of transient events. This transfer uses multiple fiber optic cables to reach Santiago, Chile, then via redundant routes to Miami, Florida, where it connects to existing high speed conduits. These links were activated in March 2018 by the AmLight consortium. Since the data crosses international borders, many groups are involved. These include the Association of Universities for Research in Astronomy (AURA, Chile, and the US), REUNA (Chile), Florida International University (US), AmLightExP (US), RNP (Brazil), and USDF (US), all of which participate in the Rubin Observatory Network Engineering Team (NET). This collaboration designs and delivers end-to-end network performance across network domains and providers.

• Illustration — 333 second-exposure image of the night sky containing 19 or more streaks due to Starlink satellite's light pollution – image from CTIO's Dark Energy Camera that has a similar field of view to the Rubin Observatory camera While taking a long exposure, a satellite can cross the field of view, leaving a streak on the image. While it is possible to model and remove a streak, the residual Poisson noise lowers the signal-to-noise ratio of the corrected pixels too much to be of scientific value. The issue came to prominence when a satellite train crossed an image taken by Cerro Tololo Inter-American Observatory (CTIO). Starlink has launched 7,000 satellites to low Earth orbit (LEO), with plans to expand to 12,000 and then to 34,400. Even if the Starlink constellation does not reach its planned size, the Project Kuiper and OneWeb LEO satellite constellations led to concern about how satellites could affect astronomical images. Estimates suggested that 30–40% of the images taken early and late at night could be compromised. This will impact science missions such as the observation of near-Earth objects. These must be observed in the same time frame as satellites as both need illumination by the Sun near twilight before they are obscured by the Earth's shadow. The Observatory has simulated altering their observing strategy to avoid satellite streaks. They found that this would increase slew times, sacrificing around 10% of observing time, to decrease the number of satellite streaks by a factor of two. Studies reported that even in the regime of very large satellite constellations (30,000 satellites), 8% of all science images would have a satellite streak, costing around 0.04% of the total number of science pixels.

• Illustration — Video beginning with two galaxies and zooming out to reveal about 10 million galaxies combining over 1100 images (0m58s) • Illustration — Trifid Nebula (top) and the Lagoon Nebula in a video combining 678 images (1min) • Illustration — A small section of the Virgo Cluster • Illustration — NGC 4261 is the large elliptical galaxy at the top of the image. • Illustration — Four examples of objects found in the Trifid Nebula and Lagoon Nebula • Illustration — The spiral galaxies NGC 4411B (left) and NGC 4411 (right) taken from "The Cosmic Treasure Chest" • Illustration — NGC 4326 • Illustration — NGC 4410

• Illustration — Clear skies at Cerro Pachón • Illustration — Construction • Illustration — Telescope mount assembly, taken from the dome during bridge crane installation • Illustration — Focal plane of Cam – wide, with 189 sensors to produce 3200-megapixel images • Illustration — Optical engineers Justin Wolfe (left) and Simon Cohen with the r filter • Illustration — Cam chilled to subzero temperatures • Illustration — Comet Leonard, the Observatory, the planet Venus, and various stars • Illustration — Night light with sky brightening due to the artificial light that can be seen as clusters of bright lights on the horizon • Illustration — From inside the observatory at night, during commissioning

• Illustration — Artist's illustration of the Rubin Observatory alert stream, launched on 24 February 2026. Icons represent individual alert types, including asteroids, supernovae, active galactic nuclei, and variable stars.