We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). 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 large, wide-field ground-based system designed to obtain repeated images covering the sky visible from Cerro Pachón 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, a 3.2-gigapixel camera, and six filters (ugrizy) covering the wavelength range 320-1050 nm. The project is in the construction phase and will begin regular survey operations by 2022. About 90% of the observing time will be devoted to a deep-wide-fast survey mode that will uniformly observe a 18,000 deg 2 region about 800 times (summed over all six bands) during the anticipated 10 yr of operations and will yield a co-added map to r∼27.5. These data will result in databases including about 32 trillion observations of 20 billion galaxies and a similar number of stars, and they will serve the majority of the primary science programs. The remaining 10% of the observing time will be allocated to special projects such as Very Deep and Very Fast time domain surveys, whose details are currently under discussion. We illustrate how the LSST science drivers led to these choices of system parameters, and we describe the expected data products and their characteristics.

Context. We report on the results of calibrating and simulating the instrumental polarization properties of the ESO VLT adaptive optics camera system NAOS/CONICA (NACO) in the Ks-band. Aims. Our goal is to understand the influence of systematic calibration effects on the time-resolved polarimetric observations of the infrared counterpart of the Galactic center super-massive black hole at the position of Sagittarius A* (Sgr A*). Methods. We use the Stokes/Mueller formalism for metallic reflections to describe the instrumental polarization. The model is compared to standard-star observations and time-resolved observations of bright sources in the Galactic center. The differences between calibration methods are simulated and tested for three polarimetric Ks-band light curves of Sgr A*. Results. We find the instrumental polarization to be highly dependent on the pointing position of the telescope and about 4% at maximum. Given the statistical uncertainties in the data acquisition, the systematic effects of the employed calibration method are negligible at high-time resolution, as it is necessary and achieved for in the case of Sgr A*. We report a polarization angle offset of 13.2 • due to a position angle offset of the λ/2-wave plate with respect to the header value that affects the calibration of NACO data taken before autumn 2009. Conclusions. With the new model of the instrumental polarization of NACO it is possible to measure the polarization with an accuracy of 1% in polarization degree. The uncertainty of the polarization angle is ≤5 • for polarization degrees ≥4%. For highly sampled polarimetric time series we find that the improved understanding of the polarization properties gives results that are fully consistent with the previously used method to derive the polarization. The small difference between the derived and the previously employed polarization calibration is well within the statistical uncertainties of the measurements, and for Sgr A* they do not affect the results from our relativistic modeling of the accretion process.

We report in this paper on the design and progress of the ESO Laser Guide Star Facility. The project will create a user facility embedded in UT4, to produce in the Earth's Mesosphere Laser Guide Stars, which extend the sky coverage of Adaptive Optics systems on the VLT UT4 telescope. Embedded into the project are provisions for multiple LGS to cope with second generation MCAO instruments.The LGSF is designed, assembled and installed by ESO in collaboration with the MPE and Max-Planck Institut für Astronomie (MPIA) in Heidelberg. MPE/MPIA are responsible for the laser system, PARSEC (Paranal Artificial Reference Source for Extended Coverage), and for the LIDAR operation mode of the LGSF. ESO is responsible for the laser room, the laser beam relay, the laser beam launch telescope with servos, and all the diagnostic and safety measures. The LGSF becomes part of, and it is governed by, the UT4 Telescope Control System. LGSF has to adopt the VLT standards and to be retrofitted on the existing UT4 telescope.The LGSF has to be upgradable to produce and control 5 Laser Guide Stars for MCAO, in 2006. The current LGSF design already embeds provisions for this upgrade.In the design of the LGSF we take advantage of the field experience matured with the MPE/MPIA ALFA system, in Calar Alto. All design areas benefit from the ALFA experience, and the LGSF becomes truly a second generation Laser Guide Star Facility. The project was kicked-off in September 2000, and has reached the Preliminary Design Review milestone on April 2 nd , 2001. At this time we are progressing toward the Final Design Review. We report on the current design solutions and tradeoffs. * send offprints requests to: dbonacci@eso.org Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/14/2015 Terms of Use: http://spiedl.org/terms Proc. SPIE Vol. 4494 277 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/14/2015 Terms of Use: http://spiedl.org/terms

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We report on the ongoing VLT Laser Guide Star Facility project, which will allow the ESO UT4 telescope to produce an artificial reference star for the Adaptive Optics systems NAOS-CONICA and SINFONI. A custom developed dye laser producing >10W CW at 589nm is installed on-board of the UT4 telescope, then relayed by means of a single mode optical fiber behind the secondary mirror, where a 500mm diameter lightweight, f/1 launch telescope is projecting the laser beam at 90 km altitude. We described the design tradeoffs and provide some details of the chosen subsystems. This paper is an update including subsystems results, to be read together with our previous paper on LGSF design description 3 .