29 research outputs found

    Precision single mode fibre integral field spectroscopy with the RHEA spectrograph

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    The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2 m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA@Subaru and progress towards the stated science goals

    Development of the single-mode fiber integral field unit for the RHEA Spectrograph

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    RHEA is a single-mode échelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. The instrument has a novel fiber feed with an integral field unit injecting into a grid of single-mode fibers reformatted to form a pseudo-slit, increasing throughput and enabling highspatial resolution observations when operating behind Subaru and the SCExAO adaptive optics system. The past 18 months have seen a replacement cable constructed for the instrument to address modal noise caused by closely packed fibers with similar path lengths. Here we detail the cable fabrication procedure, design improvements, increased precision in meeting the required sub-micron optical tolerances, throughput gains, and known remaining issues

    An innovative integral field unit upgrade with 3D-printed micro-lenses for the RHEA at Subaru

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    In the new era of Extremely Large Telescopes (ELTs) currently under construction, challenging requirements drive spectrograph designs towards techniques that efficiently use a facility's light collection power. Operating in the single-mode (SM) regime, close to the diffraction limit, reduces the footprint of the instrument compared to a conventional high-resolving power spectrograph. The custom built injection fiber system with 3D-printed micro-lenses on top of it for the replicable high-resolution exoplanet and asteroseismology spectrograph at Subaru in combination with extreme adaptive optics of SCExAO, proved its high efficiency in a lab environment, manifesting up to ~77% of the theoretical predicted performance

    Keck Planet Finder: design updates

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    The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter

    Keck Planet Finder: design updates

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    The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter

    Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

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    BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)
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