LSST Science Data Quality Analysis Subsystem Design

The Large Synoptic Survey Telescope (LSST) will have a Science Data Quality Analysis (SDQA) subsystem for vetting its unprecedented volume of astronomical image data. The SDQA subsystem inhabits three basic realms: image processing, graphical-user-interface (GUI) tools, and alarms/reporting. During pipeline image processing, SDQA data are computed for the images and astronomical sources extracted from the images, and utilized to grade the images and sources. Alarms are automatically sent, if necessary, to initiate swift response to problems found. Both SDQA data and machine-determined grades are stored in a database. At the end of a data-processing interval, e.g., nightly processing or data-release reprocessing, automatic SDQA reports are generated from SDQA data and grades queried from the database. The SDQA reports summarize the science data quality and provide feedback to telescope, camera, facility, observation-scheduling and data-processing personnel. During operations, GUI tools facilitate visualization of image and SDQA data in a variety of ways that allow a small SDQA-operations team of humans to quickly and easily perform manual SDQA on a substantial fraction of LSST data products, and possibly reassign SDQA grades as a result of the visual inspection

High performance astronomical data communications in the LSST data management system

The Large Synoptic Survey Telescope (LSST) is an 8.4m (6.5m effective), wide-field (9.6 degree2), ground-based telescope with a 3.2 GPixel camera. It will survey over 20,000 degree2 with 1,000 re-visits over 10 years in six visible bands, and is scheduled to begin full scientific operations in 2016. The Data Management System will acquire and process the images, issue transient alerts, and catalog the world's largest database of optical astronomical data. Every 24 hours, 15 terabytes of raw data will be transferred via redundant 10 Gbps fiber optics down from the mountain summit at Cerro Pachon, Chile to the Base Facility in La Serena for transient alert processing. Simultaneously, the data will be transferred at 2.5Gbps over fiber optics to the Archive Center in Champaign, Illinois for archiving and further scientific processing and creation of scientific data catalogs. Finally, the Archive Center will distribute the processed data and catalogs at 10Gbps to a number Data Access Centers for scientific ,educational, and public access. Redundant storage and network bandwidth is built into the design of the system. The current networking acquistiion strategy involves leveraging existing dark fiber to handle within Chile, Chile - U.S. and within U.S. links. There are a significant number of carriers and networks involved and coordinating the acquisition, deployment, and operations of this capability. Advanced protocols are being investigated during our Research and Development phase to address anticipated challenges in effective utilization. We describe the data communications requirements, architecture, and acquisition strategy in this paper

High performance astronomical data communications in the LSST data management system

The Large Synoptic Survey Telescope (LSST) is an 8.4m (6.5m effective), wide-field (9.6 degree2), ground-based telescope with a 3.2 GPixel camera. It will survey over 20,000 degree2 with 1,000 re-visits over 10 years in six visible bands, and is scheduled to begin full scientific operations in 2016. The Data Management System will acquire and process the images, issue transient alerts, and catalog the world's largest database of optical astronomical data. Every 24 hours, 15 terabytes of raw data will be transferred via redundant 10 Gbps fiber optics down from the mountain summit at Cerro Pachon, Chile to the Base Facility in La Serena for transient alert processing. Simultaneously, the data will be transferred at 2.5Gbps over fiber optics to the Archive Center in Champaign, Illinois for archiving and further scientific processing and creation of scientific data catalogs. Finally, the Archive Center will distribute the processed data and catalogs at 10Gbps to a number Data Access Centers for scientific ,educational, and public access. Redundant storage and network bandwidth is built into the design of the system. The current networking acquistiion strategy involves leveraging existing dark fiber to handle within Chile, Chile - U.S. and within U.S. links. There are a significant number of carriers and networks involved and coordinating the acquisition, deployment, and operations of this capability. Advanced protocols are being investigated during our Research and Development phase to address anticipated challenges in effective utilization. We describe the data communications requirements, architecture, and acquisition strategy in this paper

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie