42 research outputs found
739 observed NEAs and new 2-4m survey statistics within the EURONEAR network
We report follow-up observations of 477 program Near-Earth Asteroids (NEAs)
using nine telescopes of the EURONEAR network having apertures between 0.3 and
4.2 m. Adding these NEAs to our previous results we now count 739 program NEAs
followed-up by the EURONEAR network since 2006. The targets were selected using
EURONEAR planning tools focusing on high priority objects. Analyzing the
resulting orbital improvements suggests astrometric follow-up is most important
days to weeks after discovery, with recovery at a new opposition also valuable.
Additionally we observed 40 survey fields spanning three nights covering 11 sq.
degrees near opposition, using the Wide Field Camera on the 2.5m Isaac Newton
Telescope (INT), resulting in 104 discovered main belt asteroids (MBAs) and
another 626 unknown one-night objects. These fields, plus program NEA fields
from the INT and from the wide field MOSAIC II camera on the Blanco 4m
telescope, generated around 12,000 observations of 2,000 minor planets (mostly
MBAs) observed in 34 square degrees. We identify Near Earth Object (NEO)
candidates among the unknown (single night) objects using three selection
criteria. Testing these criteria on the (known) program NEAs shows the best
selection methods are our epsilon-miu model which checks solar elongation and
sky motion and the MPC's NEO rating tool. Our new data show that on average 0.5
NEO candidates per square degree should be observable in a 2m-class survey (in
agreement with past results), while an average of 2.7 NEO candidates per square
degree should be observable in a 4m-class survey (although our Blanco
statistics were affected by clouds). At opposition just over 100 MBAs (1.6
unknown to every 1 known) per square degree are detectable to R=22 in a 2m
survey based on the INT data, while our two best ecliptic Blanco fields away
from opposition lead to 135 MBAs (2 unknown to every 1 known) to R=23.Comment: Published in Planetary and Space Sciences (Sep 2013
The Fornax Cluster VLT Spectroscopic Survey. I â VIMOS spectroscopy of compact stellar systems in the Fornax core region
We present the results of a wide spectroscopic survey aimed at detecting extragalactic globular clusters (GCs) in the core of the Fornax cluster. About 4500 low resolution spectra (from 4800 to 10000 Ă
) were observed in 25 VLT/VIMOS masks covering the central 1 deg2 around the dominant galaxy NGC 1399 corresponding to âŒ175 kpc galactocentric radius. We describe the methodology used for data reduction and data analysis. We found a total of 387 unique physical objects (372 GCs and 15 ultra compact dwarfs) in the field covered by our observations. Most of these objects lie in the region of NGC1399 halo, with only 10% likely belonging to other giant galaxies 48 of these objects have a literature counterpart. The new VIMOS dataset is complementary to the many GC catalogues already present in the literature and it brings the total number of tracer particles around NGC 1399 to more than 1130 objects. With this comprehensive radial velocity sample we have found that the velocity dispersion of the GC population (equally for red and blue GC populations) shows a relatively sharp increase from low velocity dispersion (âŒ250 â 350âkm s) to high velocity dispersion (âŒ300 â 400âkm s) at projected radius of â10 arcmin (âŒ60 kpc) from the galaxy centre. This suggests that at a projected radius of â60 kpc both blue and red GC populations begin to be governed by the dominating Fornax cluster potential, rather than by the central NGC 1399 galaxy potential. This kinematic evidence corroborates similar results found using surface brightness analysis and planetary nebulae kinematics
Seeing eye to eye: social augmented reality and shared decision making in the marketplace
Firms increasingly seek to improve the online shopping experience by enabling customers to exchange product recommendations through social augmented reality (AR). We utilize socially situated cognition theory and conduct a series of five studies to explore how social AR supports shared decision making in recommenderâdecision maker dyads. We demonstrate that optimal configurations of social AR, that is, a static (vs. dynamic) point-of-view sharing format matched with an image-enhanced (vs. text-only) communicative act, increase recommendersâ comfort with providing advice and decision makersâ likelihood of using the advice in their choice. For both, these effects are due to a sense of social empowerment, which also stimulates recommendersâ desire for a product and positive behavioral intentions. However, recommendersâ communication motives impose boundary conditions. When recommenders have strong impression management concerns, this weakens the effect of social empowerment on recommendation comfort. Furthermore, the stronger a recommenderâs persuasion goal, the less likely the decision maker is to use the recommendation in their choice
A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and Stellar Population Characterization
The center of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) hosts a nuclear star cluster (NSC), M54, which is the only galaxy nucleus that can be resolved into individual stars at optical wavelengths. It is thus a key target for understanding the formation of NSCs and their relation to globular clusters (GCs). We present a large Multi-Unit Spectroscopic Explorer data set that covers M54 out to ~2.5 half-light radius, from which we extracted the spectra of ~6600 cluster member stars. We use these data in combination with Hubble Space Telescope photometry to derive age and metallicity for each star. The stellar populations show a well-defined ageâmetallicity relation, implying an extended formation history for the central region of Sgr dSph. We classify these populations into three groups, all with the same systemic velocity: young metal-rich (YMR; 2.2 Gyr, [Fe/H] = â0.04); intermediate-age metal-rich (IMR; 4.3 Gyr, [Fe/H] = â0.29); and old metal-poor (OMP; 12.2 Gyr, [Fe/H] = â1.41). The YMR and OMP populations are more centrally concentrated than the IMR population, which are likely stars of the Sgr dSph. We suggest that the OMP population is the result of accretion and merging of two or more old and metal-poor GCs dragged to the center by dynamical friction. The YMR is consistent with being formed by in situ star formation in the nucleus. The ages of the YMR population suggest that it may have been triggered into forming when the Sgr dSph began losing its gas during the most recent interaction with the Milky Way, ~3 Gyr ago
ColeccĂon de Reales Ordenes y Disposiciones de las autoridades superiores en la isla de Cuba. : Publicadas en la Gaceta de la Habana, año 1857.
Copia digital. España : Ministerio de Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 202
Variance optimal hedging in the Black-Scholes model for a given number of transactions
Theme 4 - Simulation et optimisation de systemes complexes - Projet MATHFISIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 14802 E, issue : a.1999 n.3767 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
A strategic framework
Customer experience (CX) has emerged as a sustainable source of competitive differentiation. Recent developments in big data analytics (BDA) have exposed possibilities to unlock customer insights for customer experience management (CXM). Research at the intersection of these two fields is scarce and there is a need for conceptual work that (1) provides an overview of opportunities to use BDA for CXM and (2) guides management practice and future research. The purpose of this paper is therefore to develop a strategic framework for CXM based on CX insights resulting from BDA. Our conceptualisation is comprehensive and is particularly relevant for researchers and practitioners who are less familiar with the potential of BDA for CXM. For managers, we provide a step-by-step guide on how to kick-start or implement our strategic framework. For researchers, we propose some opportunities for future studies in this promising research area.peerReviewe