Search results for "OBS"
showing 10 items of 6542 documents
Exomorphism of jacobsite precipitates in bixbyite single crystals from the Thomas Range in Utah
2021
Abstract Naturally occurring single crystals of bixbyite, (Fe,Mn)2O3, from the Thomas Mountain Range in Utah, U.S.A., were studied via (scanning) transmission electron microscopy (S)TEM. With up to 5 cm edge length, these mineral specimens are the largest bixbyite crystals found worldwide. Their hexahedral shapes are often modified by {211} facets at the corners and small {211} truncations along their cube edges. Characteristic lamellar defects, running parallel to the {100} planes, can be observed via TEM imaging. The defects are, according to EDS analyses, attributed to the tetragonal manganese silicate braunite, Mn7[SiO12]. In the present study, electron nano-diffraction and atomic resol…
Quantum dynamics of 16O in collision with ortho- and para-17O17O
2017
Abstract We report full quantum dynamical observables, such as integral and differential cross sections and rate constants, for the 16 O + 17 O 17 O reactive collision process. We particularly emphasize the effect coming from the nonzero nuclear spin of 17 O, leading to two nuclear spin isomers of 34 O 2 , ortho- and para- 34 O 2 which can be studied independently and behave differently. A comparison with the 16 O + 18 O 18 O collision is given. We find that processes involving 17 O 17 O are always faster than with 18 O 18 O.
Cosmic-Ray Anisotropies in Right Ascension Measured by the Pierre Auger Observatory
2020
We present measurements of the large-scale cosmic-ray anisotropies in right ascension, using data collected by the surface detector array of the Pierre Auger Observatory over more than 14 years. We determine the equatorial dipole component, ~d⊥, through a Fourier analysis in right ascension that includes weights for each event so as to account for the main detector-induced systematic effects. For the energies at which the trigger efficiency of the array is small, the “East-West” method is employed. Besides using the data from the array with detectors separated by 1500 m, we also include data from the smaller but denser sub-array of detectors with 750 m separation, which allows us to extend …
A Search for Ultra-high-energy Neutrinos from TXS 0506+056 Using the Pierre Auger Observatory
2020
Results of a search for ultra-high-energy neutrinos with the Pierre Auger Observatory from the direction of the blazar TXS 0506+056 are presented. They were obtained as part of the follow-up that stemmed from the detection of high-energy neutrinos and gamma rays with IceCube, Fermi-LAT, MAGIC, and other detectors of electromagnetic radiation in several bands. The Pierre Auger Observatory is sensitive to neutrinos in the energy range from 100 PeV to 100 EeV and in the zenith-angle range from θ = 60° to θ = 95°, where the zenith angle is measured from the vertical direction. No neutrinos from the direction of TXS 0506+056 have been found. The results were analyzed in three periods: One of 6 m…
A 3-Year Sample of Almost 1,600 Elves Recorded Above South America by the Pierre Auger Cosmic-Ray Observatory
2020
The time and location of the 1,598 verified and reconstructed elves, used for the analysis showcased in this paper, are publicly available on the website of the Pierre Auger Observatory (https://www.auger.org/ index.php/science/data). We wish to thank the World Wide Lightning Location Network (http://wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning location data used in this paper. We acknowledge Robert Marshall for providing one of the most advanced elve simulations to the public, a key tool in understanding the elves observed by the Pierre Auger Observatory. The successful installation, commissioning, and operation of the Pierre Auger Ob…
Observational data and orbits of the asteroids discovered at the Baldone Observatory in 2015–2018
2020
AbstractThis paper is devoted to the discovery of 37 asteroids at the Baldone Astrophysical Observatory (MPC 069) from 2015 to 2018, and one of dynamically interesting Mars-crosser (MC) observed at the Baldone Astrophysical Observatory, namely 2008 LX16. In Baldone Observatory, was independently discovered the Near-Earth Object 2018 GE3 on the image of 13 April 2018. Also, the NEO 2006 VB14 was observed doing its astrometry and photometry. Moreover, we observed asteroids 1986 DA and 2014 LJ1. We computed orbits and analyzed the orbital evolution of these asteroids. 566 positions and photometric observations of NEO objects 345705 (2006 VB14) and 6178 (1986 DA) were obtained with Baldone Schm…
Gravitational-wave Detection and Parameter Estimation for Accreting Black-hole Binaries and Their Electromagnetic Counterpart
2020
We study the impact of gas accretion on the orbital evolution of black-hole binaries initially at large separation in the band of the planned Laser Interferometer Space Antenna (LISA). We focus on two sources: (i)~stellar-origin black-hole binaries~(SOBHBs) that can migrate from the LISA band to the band of ground-based gravitational-wave observatories within weeks/months; and (ii) intermediate-mass black-hole binaries~(IMBHBs) in the LISA band only. Because of the large number of observable gravitational-wave cycles, the phase evolution of these systems needs to be modeled to great accuracy to avoid biasing the estimation of the source parameters. Accretion affects the gravitational-wave p…
IceCube search for neutrinos coincident with compact binary mergers from LIGO-Virgo's first gravitational-wave transient catalog
2020
Using the IceCube Neutrino Observatory, we search for high-energy neutrino emission coincident with compact binary mergers observed by the LIGO and Virgo gravitational-wave (GW) detectors during their first and second observing runs. We present results from two searches targeting emission coincident with the sky localization of each GW event within a 1000 s time window centered around the reported merger time. One search uses a model-independent unbinned maximum-likelihood analysis, which uses neutrino data from IceCube to search for pointlike neutrino sources consistent with the sky localization of GW events. The other uses the Low-Latency Algorithm for Multi-messenger Astrophysics, which …
Subarcsecond Location of IGR J17480-2446 with Rossi XTE
2012
On 2010 October 13, the X-ray astronomical satellite Rossi XTE, during the observation of the newly discovered accretion powered X-ray pulsar IGR J17480--2446, detected a lunar occultation of the source. From knowledge of lunar topography and Earth, Moon, and spacecraft ephemeris at the epoch of the event, we determined the source position with an accuracy of 40 mas (1{\sigma} c.l.), which is interesting, given the very poor imaging capabilities of RXTE (\sim 1\circ). For the first time, using a non-imaging X-ray observatory, the position of an X-ray source with a subarcsecond accuracy is derived, demonstrating the neat capabilities of a technique that can be fruitfully applied to current a…
Anticipating the impact of pitfalls in kinetic biodegradation parameter estimation from substrate depletion curves of organic pollutants
2019
[EN] Accurate and reliable estimation of kinetic parameters of pollutant biodegradation processes is essential for environmental and health risk assessment. Common biodegradation models proposed in the literature, such as the nonlinear Monod equation and its simplified versions (e.g. Michaelis-Menten-like and first-order equations), are problematic in terms of accuracy of kinetic parameters due to the parameter correlation. However, a comparison between these models in terms of accuracy and reliability, related to data imprecision, has not been performed in the literature. This task is necessary, mainly because the model selection cannot be straightforward, as shown in this work. To facilit…