139 research outputs found
The 2MASS Redshift Survey in the Zone of Avoidance
Get PDFThe Two Micron All-Sky Survey (2MASS) Redshift Survey was started two decades ago with the goal of mapping the three-dimensional distribution of an all-sky flux-limited (K s < 11.75 mag) sample of ~45,000 galaxies. Our first data release presented an unprecedented uniform coverage for most of the celestial sphere, with redshifts for ~98% of our sample. However, we were missing redshifts for ~18% of the catalog entries that were located within the "Zone of Avoidance" ()—an important region of the sky for studies of the large-scale structure and cosmic flows. In this second and final data release, we present redshifts for all 1041 2MRS galaxies that previously lacked this information, as well as updated measurements for 27 others.Fil: Macri, Lucas M.. Texas A&M University; Estados UnidosFil: Kraan Korteweg, Renee Christine. University of Cape Town; SudáfricaFil: Lambert, Trystan. South African Astronomical Observatory; SudáfricaFil: Alonso, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Berlind, Perry. South African Astronomical Observatory; SudáfricaFil: Calkins, Michael. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Erdogdu, Pirin. University College London. Department of Physics and Astronomy; Reino UnidoFil: Falco, Emilio. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Jarrett, Thomas. University of Cape Town; SudáfricaFil: Mink, Jessica. Harvard-Smithsonian Center for Astrophysics; Estados Unido
Control Of Algal Standing Crop By P And N In The Clark Fork River
Get PDFIn the mid and late 1980\u27 s, attached algae levels in the Clark Fork of the Columbia River varied from unnoticeable to extreme nuisance levels. Thi.5 study addressed the question: are P and N levels low enough long enough to limit algal growth and standing crop in this river? If so, river reaches with nuisance levels may improve if nutrient levels are lowered, and high quality reache.5 may worsen if nutrient levels are allowed to increase. Because the Clark Fork often exhibits N and P levels thought to saturate algal growth, there was doubt that nutrient management would affect algal levels. Through the use of artificial stream fertilization experiments, this study showed that the standing crop of these attached algal communities saturate at much higher nutrient levels than does growth. At most river sites from Sept.1987 to 1989, dissolved P and N were almost always below levels that saturate algal standing crop. The ratio of dissolved N:P in the water suggested that N limitation, P limitation or a balance between the two existed for significant periods of time at almost all sites. Hence management of both N and P may reduce nuisance levels (when other factors are not limiting) and are important to protecting high quality areas.
Note: This presentation was both an oral presentation as well as a poster
Multiepoch Detections of the Extended Atmosphere and Transmission Spectra of KELT-9b with a 1.5 m Telescope
Get PDFIrradiated Jovian atmospheres are complex and dynamic and can undergo temporal variations due to the close proximity of their parent stars. Of the Jovian planets that have been cataloged to date, KELT-9b is the hottest gas giant known, with an equilibrium temperature of 4050 K. We probe the temporal variability of transmission spectroscopic signatures from KELT-9b via a set of archival multiyear ground-based transit observations, performed with the TRES facility on the 1.5 m reflector at the Fred Lawrence Whipple Observatory. Our observations confirm past detections of Fe i, Fe ii, and Mg i over multiple epochs, in addition to excess absorption at Hα, which is an indicator for ongoing mass loss. From our multiyear data set, the Hα light curve consistently deviates from a standard transit and follows a “W” shape that is deeper near ingress and egress and shallower midtransit. To search for and quantify any seasonal variations that may be present, we parameterize a “cometary tail” model to fit for the Hα transit. We find no detectable variations between the different observed epochs. Though a “cometary tail” describes the Hα flux variations well, we note that such a scenario requires a high density of neutral hydrogen in the n = 2 excited state far beyond the planetary atmosphere. Other scenarios, such as center-to-limb variations larger than that expected from 1D atmosphere models, may also contribute to the observed Hα transit shape. These multiepoch observations highlight the capabilities of small telescopes to provide temporal monitoring of the dynamics of exoplanet atmospheres
Control of Algal Standing Crop by P and N in the Clark Fork River
Get PDFIn the mid and late 1980\u27 s, attached algae levels in the Clark Fork of the Columbia River varied from unnoticeable to extreme nuisance levels. Thi.5 study addressed the question: are P and N levels low enough long enough to limit algal growth and standing crop in this river? If so, river reaches with nuisance levels may improve if nutrient levels are lowered, and high quality reache.5 may worsen if nutrient levels are allowed to increase. Because the Clark Fork often exhibits N and P levels thought to saturate algal growth, there was doubt that nutrient management would affect algal levels. Through the use of artificial stream fertilization experiments, this study showed that the standing crop of these attached algal communities saturate at much higher nutrient levels than does growth. At most river sites from Sept.1987 to 1989, dissolved P and N were almost always below levels that saturate algal standing crop. The ratio of dissolved N:P in the water suggested that N limitation, P limitation or a balance between the two existed for significant periods of time at almost all sites. Hence management of both N and P may reduce nuisance levels (when other factors are not limiting) and are important to protecting high quality areas
Capability augmentation for heterogeneous dynamic teaming with temporal logic tasks
No full textFirst author draf
Optical spectra of nearby M dwarfs
No full textOptical spectra obtained with the FAST instrument at Fred Lawrence Whipple Observatory, obtained as part of the MEarth Project. Spectra are of nearby M dwarfs. Files are named by 2MASS ID (minus the 2MASS part), with the file format of:
twomassid.program.year.date.ms.fits
where program indicates which of the two FAST programs (204 and 222) the spectra derive from, and the year and date (month+day) indicate the date of the observations.
Data from Program 204 were first published in West et al. (2015), and were re-analyzed in Newton et al. (2017). Data from Program 222 were first published in Newton et al. (2017)
Efficient semi-supervised and active learning of disjunctions
No full textWe provide efficient algorithms for learning disjunctions in the semi-supervised setting under a natural regularity assumption introduced by (Balcan & Blum, 2005). We prove bounds on the sample complexity of our algorithms under a mild restriction on the data distribution. We also give an active learning algorithm with improved sample complexity and extend all our algorithms to the random classification noise setting. Copyright 2013 by the author(s).link_to_subscribed_fulltex
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey:including covariance matrix errors
Get PDFJP acknowledges support from the UK Science & Technology Facilities Council (STFC) through the consolidated grant ST/K0090X/1 and from the European Research Council through the ‘Starting Independent Research’ grant 202686, MDEPUGS. AGS acknowledges support from the Trans-regional Collaborative Research Centre TR33 ‘The Dark Universe’ of the German Research Foundation (DFG).We present improved methodology for including covariance matrices in the error budget of Baryon Oscillation Spectroscopic Survey (BOSS) galaxy clustering measurements, revisiting Data Release 9 (DR9) analyses, and describing a method that is used in DR10/11 analyses presented in companion papers. The precise analysis method adopted is becoming increasingly important, due to the precision that BOSS can now reach: even using as many as 600 mock catalogues to estimate covariance of two-point clustering measurements can still lead to an increase in the errors of ∼20 per cent, depending on how the cosmological parameters of interest are measured. In this paper, we extend previous work on this contribution to the error budget, deriving formulae for errors measured by integrating over the likelihood, and to the distribution of recovered best-fitting parameters fitting the simulations also used to estimate the covariance matrix. Both are situations that previous analyses of BOSS have considered. We apply the formulae derived to baryon acoustic oscillation (BAO) and redshift-space distortion (RSD) measurements from BOSS in our companion papers. To further aid these analyses, we consider the optimum number of bins to use for two-point measurements using the monopole power spectrum or correlation function for BAO, and the monopole and quadrupole moments of the correlation function for anisotropic-BAO and RSD measurements.Peer reviewe
Searching for Exoplanets Born Outside the Milky Way: VOYAGERS Survey Design
No full textAbstract Observations over the past few decades have found that planets are common around nearby stars in our Galaxy, but little is known about planets that formed outside the Milky Way. We describe the design and early implementation of a survey to test whether planets also exist orbiting the remnant stars of ancient dwarf galaxies that merged with the Milky Way, and if so, how they differ from their Milky Way counterparts. VOYAGERS ( Views Of Yore —Ancient Gaia-enceladus Exoplanet Revealing Survey ) is a radial velocity (RV) search using precision spectrographs to discover exoplanets orbiting very low metallicity (−2.8 < [Fe/H] ≤ −0.8) stars born in the dwarf galaxy Enceladus, which merged with the Milky Way galaxy about 10 Gyr ago. A sample of 22 candidates have been screened from a catalog of Gaia–Enceladus–Sausage (GES) members using a combination of stellar properties and reconnaissance observations from the TRES spectrograph. Precision RV measurements have been initiated using the NEID, HARPS-N, and CARMENES spectrographs. We plan to focus most upcoming observations on 10 main sequence targets. Data collection is well underway, with 778 observations on 22 candidates (385 of which are on 10 focus targets), but far from complete. This survey is designed to be sensitive to sub-Neptune mass planets with periods up to hundreds of days. We note that the RV analysis gives mass multiplied by sin ( inclination ) or the minimum mass for exoplanets. The expected survey yield is three planets, assuming that occurrence rates are similar to those in the Milky Way and taking into account the degeneracy with inclination in our yield models. Our survey is designed to detect at least one exoplanet if occurrence rates are similar to known Milky Way exoplanets or, if no exoplanets are discovered, to rule out a Milky Way-like planet population in GES with 95% confidence level
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