28 research outputs found

    Gemini multi-conjugate adaptive optics system review II: Commissioning, operation and overall performance

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    The Gemini Multi-conjugate Adaptive Optics System - GeMS, a facility instrument mounted on the Gemini South telescope, delivers a uniform, near diffraction limited images at near infrared wavelengths (0.95 microns- 2.5 microns) over a field of view of 120 arc seconds. GeMS is the first sodium layer based multi laser guide star adaptive optics system used in astronomy. It uses five laser guide stars distributed on a 60 arc seconds square constellation to measure for atmospheric distortions and two deformable mirrors to compensate for it. In this paper, the second devoted to describe the GeMS project, we present the commissioning, overall performance and operational scheme of GeMS. Performance of each sub-system is derived from the commissioning results. The typical image quality, expressed in full with half maximum, Strehl ratios and variations over the field delivered by the system are then described. A discussion of the main contributor to performance limitation is carried-out. Finally, overheads and future system upgrades are described.Comment: 20 pages, 11 figures, accepted for publication in MNRA

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

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    (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 deg2^2 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 5σ\sigma point-source depth in a single visit in rr will be ∌24.5\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 deg2^2 with ÎŽ<+34.5∘\delta<+34.5^\circ, and will be imaged multiple times in six bands, ugrizyugrizy, 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 deg2^2 region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to r∌27.5r\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

    Interim 2017/18 influenza seasonal vaccine effectiveness: Combined results from five European studies

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    Between September 2017 and February 2018, influenza A(H1N1)pdm09, A(H3N2) and B viruses (mainly B/Yamagata, not included in 2017/18 trivalent vaccines) co-circulated in Europe. Interim results from five European studies indicate that, in all age groups, 2017/18 influenza vaccine effectiveness was 25 to 52% against any influenza, 55 to 68% against influenza A(H1N1)pdm09, -42 to 7% against influenza A(H3N2) and 36 to 54% against influenza B. 2017/18 influenza vaccine should be promoted where influenza still circulates

    Chiral ligand-exchange chromatography for diastereo-enantio separation of exametazime

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    The diastereo-enantio separation of isomeric mixtures of exametazime (HM-PAO) by liquid chromatography is described using an achiral sorbent (RP-18). A chiral eluent with the initial complex of Cu(II) and the optically active selector N,N-dimethyl-l-phenylalanine (l-DM-PhA), based on the ligand-exchange principle, has been applied. The separation is based on the presence of the immobilized binary complex Cu(l-DM-PhA

    Science readiness of the Gemini MCAO system: GeMS

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    The Gemini Multi-Conjugate Adaptive Optics System (GeMS) began its on-sky commissioning in January 2011. The system provides high order wide-field corrections using a constellation of five Laser Guide Stars. In December 2011, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band) over an 87 x 87 arcsecond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: "GeMS on-sky results", Rigaut et al.1 Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS

    Gemini South multi-conjugate adaptive optics (GeMS) laser guide star facility on-sky performance results

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    With two to three deformable mirrors, three Natural Guide Stars (NGS) and five sodium Laser Guide Stars (LGS), the Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS) will be the first facility-class MCAO capability to be offered for regular science observations starting in 2013A. The engineering and science commissioning phase of the project was kicked off in January 2011 when the Gemini South Laser Guide Star Facility (GS LGSF) propagated its 50W laser above the summit of Cerro PachĂłn, Chile. GeMS commissioning has proceeded throughout 2011 and the first half of 2012 at a pace of one 6- to 10-night run per month with a 5-month pause during the 2011 Chilean winter. This paper focuses on the LGSF-side of the project and provides an overview of the LGSF system and subsystems, their top-level specifications, design, integration with the telescope, and performance throughout commissioning and beyond. Subsystems of the GS LGSF include: (i) a diode-pumped solid-state 1.06+1.32 micron sum-frequency laser capable of producing over 50W of output power at the sodium wavelength (589nm); (ii) Beam Transfer Optics (BTO) that transport the 50W beam up the telescope, split the beam five-ways and configure the five 10W beams for projection by the Laser Launch Telescope (LLT) located behind the Gemini South 8m telescope secondary mirror; and (iii) a variety of safety systems to ensure safe laser operations for observatory personnel and equipment, neighbor observatories, as well as passing aircrafts and satellites

    2015/16 I-MOVE/I-MOVE+ multicentre case-control study in Europe: Moderate vaccine effectiveness estimates against influenza A(H1N1)pdm09 and low estimates against lineage-mismatched influenza B among children

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    During the 2015/16 influenza season in Europe, the cocirculating influenza viruses were A(H1N1)pdm09 and B/Victoria, which was antigenically distinct from the B/Yamagata component in the trivalent influenza vaccine.MethodsWe used the test-negative design in a multicentre case-control study in twelve European countries to measure 2015/16 influenza vaccine effectiveness (VE) against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza. General practitioners swabbed a systematic sample of consulting ILI patients and a random sample of influenza-positive swabs was sequenced. We calculated adjusted VE against influenza A(H1N1)pdm09, A(H1N1)pdm09 genetic group 6B.1 and influenza B overall and by age group.ResultsWe included 11430 ILI patients, of which 2272 were influenza A(H1N1)pdm09 and 2901 were influenza B cases. Overall VE against influenza A(H1N1)pdm09 was 32.9% (95% CI: 15.5-46.7). Among those aged 0-14, 15-64 and 65years, VE against A(H1N1)pdm09 was 31.9% (95% CI: -32.3 to 65.0), 41.4% (95% CI: 20.5-56.7) and 13.2% (95% CI: -38.0 to 45.3), respectively. Overall VE against influenza A(H1N1)pdm09 genetic group 6B.1 was 32.8% (95% CI: -4.1 to 56.7). Among those aged 0-14, 15-64 and 65years, VE against influenza B was -47.6% (95% CI: -124.9 to 3.1), 27.3% (95% CI: -4.6 to 49.4) and 9.3% (95% CI: -44.1 to 42.9), respectively.ConclusionsVaccine effectiveness (VE) against influenza A(H1N1)pdm09 and its genetic group 6B.1 was moderate in children and adults, and low among individuals 65years. Vaccine effectiveness (VE) against influenza B was low and heterogeneous among age groups. More information on effects of previous vaccination and previous infection is needed to understand the VE results against influenza B in the context of a mismatched vaccine
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