Showing papers by "Royal Institute and Observatory of the Spanish Navy published in 2001"
TL;DR: A new algorithm, developed at the Plataforma Solar de Almeria, which combines these two characteristics of accuracy and simplicity, is presented and allows of the true solar vector to be determined with an accuracy of 0.5 minutes of arc for the period 1999–2015.
367 citations
International Trademark Association1, Spanish National Research Council2, Russian Academy of Sciences3, Isaac Newton Institute4, Danish Space Research Institute5, Royal Institute and Observatory of the Spanish Navy6, Stony Brook University7, University of Copenhagen8, Academy of Sciences of the Czech Republic9, University of Oxford10, German Aerospace Center11, Universities Space Research Association12, University of Milan13, Universities Research Association14, University of Tübingen15, Clemson University16, European Southern Observatory17, University of Barcelona18, University of Jaén19, University of Manchester20, Harvard University21, Queen's University Belfast22, University of California, Berkeley23
TL;DR: The optical afterglow of the intense gamma-ray burst GRB 991208 was observed for 2.1 days after the event and continued until 4 Apr 2000.
Abstract: Broad-band optical observations of the extraordi- narily bright optical afterglow of the intense gamma-ray burst GRB 991208 started � 2.1 days after the event and continued until 4 Apr 2000. The flux decay constant of the optical after- glow in the R-band is 2.30 ± 0.07 up to � 5 days, which
96 citations
European Southern Observatory1, Danish Space Research Institute2, University of Copenhagen3, University of Oulu4, University of Notre Dame5, Durham University6, Subaru7, University of Amsterdam8, University of Liège9, Universities Space Research Association10, Royal Institute and Observatory of the Spanish Navy11, Spanish National Research Council12, International Trademark Association13, Goddard Space Flight Center14, University of Turku15, University of California, Berkeley16, University of Tromsø17, University of Hertfordshire18, Kyoto University19
TL;DR: In this paper, the optical transient of the long-duration gamma-ray burst GRB 000926 was detected independently with the Nordic Optical Telescope and at Calar Alto 22.2 hours after the burst.
Abstract: We present the discovery of the Optical Transient (OT) of the long{duration gamma-ray burst GRB 000926. The optical transient was detected independently with the Nordic Optical Telescope and at Calar Alto 22.2 hours after the burst. At this time the magnitude of the transient was R =1 9:36. The transient faded with ad ecay slope of about 1:7 during the rst two days after which the slope increased abruptly (within a few hours) to about 2:4. The light-curve started to flatten o after about a week indicating the presence of an underlying extended object. This object was detected in a deep image obtained one month after the GRB at R =2 3:87 0:15 and consists of several compact knots within about 5 arcsec. One of the knots is spatially coin- cident with the position of the OT and hence most likely belongs to the host galaxy. Higher resolution imaging is needed to resolve whether all the compact knots belong to the host galaxy or to several independent objects. In a separate paper we present a discussion of the optical spectrum of the OT, and its inferred redshift (Mller et al., in prep.).
72 citations
TL;DR: In this article, the effect of thickness variation on the optical reflection spectrum of a thin dielectric film covering a thick non-absorbing substrate, is analyzed in detail, and analytical expressions are presented for such a reflection spectrum and its upper and lower envelopes.
Abstract: Thickness inhomogeneities in thin films have a large influence on their optical transmission and reflection spectra. If not taken into account, this may lead to rather large calculated values for the absorption coefficient or the erroneous presence of an absorption-band tail, as well as to significant errors in the calculated values of the refractive index and the film thickness. The effect of thickness variation on the optical reflection spectrum of a thin dielectric film covering a thick non-absorbing substrate, is analysed in detail in this paper, and analytical expressions are presented for such a reflection spectrum and its upper and lower envelopes. A method is suggested for determining the refractive index n(λ) and the extinction coefficient k(λ), as well as the average thickness and the thickness variation, of a thin dielectric film with variable thickness, by using only the two envelopes of the corresponding shrunk reflection spectrum. This method is used for the geometrical and optical characterization of thermally-evaporated amorphous chalcogenide films, deposited on glass substrates.
40 citations
TL;DR: MAGIC (Meteorological Applications of GPS Integrated Column Water Vapor Measurements in the Western Mediterranean) is a 3 year project for research on deriving and validating robust GPS integrated water vapor and zenith tropospheric delay data sets and developing methods to assimilate the data into numerical weather prediction models and test their impact.
Abstract: MAGIC (Meteorological Applications of GPS Integrated Column Water Vapor Measurements in the Western Mediterranean) is a 3 year project financed in part by the European Commission for research on deriving and validating robust GPS integrated water vapor (IWV) and zenith tropospheric delay (ZTD) data sets and developing methods to assimilate the data into numerical weather prediction models (NWP) and test their impact. It was conceived independently from the COST 716 action, which seeks to coordinate research in the domain at an international scale, but addresses some of the same objectives. This has led to a productive cooperation between the two initiatives and their participants, and motivated the decision of MAGIC participants to provide research results as part of the COST demonstration system. Currently a database of 1.5 years of ZTD data are available on the MAGIC web site which has been validated through comparisons with radiosondes which gives differences with a standard deviation of 10 mm ZTD or the equivalent error in IWV of 1.6 kg/m2. NWP assimilation tests will be carried out in the final year of the project.
31 citations
TL;DR: In systems with two degrees of freedom, Arnold's theorem is used for studying nonlinear stability of the origin when the quadratic part of the Hamiltonian is a nondefinite form, and in these cases, the stability is determined from analysis of the normalized phase flow.
Abstract: In systems with two degrees of freedom, Arnold's theorem is used for studying nonlinear stability of the origin when the quadratic part of the Hamiltonian is a nondefinite form. In that case, a previous normalization of the higher orders is needed, which reduces the Hamiltonian to homogeneous polynomials in the actions. However, in the case of resonances, it could not be possible to bring the Hamiltonian to the normal form required by Arnold's theorem. In these cases, we determine the stability from analysis of the normalized phase flow. Normalization up to an arbitrary order by Lie-Deprit transformation is carried out using a generalization of the Lissajous variables.
24 citations
TL;DR: The Spanish Exclusive Economic Zone (ZEEE) Project as discussed by the authors was the first phase of this extensive geophysical survey, which focused on the Balearic Sea and the Valencia Trough in the Western Mediterranean (Figure l).
Abstract: The most intensive mapping to date of the sea floor off Spain's coast is being undertaken by a Spanish government team. The first phase of this extensive geophysical survey, called the Spanish Exclusive Economic Zone (ZEEE) Project, was completed in February 2000 and focused on the Balearic Sea and the Valencia Trough in the Western Mediterranean (Figure l). The geomagnetic data acquired for the Valencia Trough area has been reduced and stored as a data base, and seven scalar magnetic anomaly maps have been produced. Four maps with scales of 1:200.000 were published in 1999 and two more will soon be printed. A map of the entire area at a scale of 1:500.000 is planned for 2001. All of the maps offer a complete and up-to-date overview of the region's magnetic character.
2 citations
01 Jan 2001
TL;DR: In this article, the basic dynamics associated with a simple model of a dust particle interacting with a planetary gravitational field, solar radiation pressure and a constant magnetic field were examined, and the presence of global equilibrium points that are analogous to the Lagrangian equilibria of the circular restricted three-body problem was found.
Abstract: We examine the basic dynamics associated with a simple model of a dust particle interacting with a planetary gravitational field, solar radiation pressure and a constant magnetic field. We find the presence of global equilibrium points that are analogous to the Lagrangian equilibria of the circular restricted three-body problem.
1 citations
Royal Institute and Observatory of the Spanish Navy1, Spanish National Research Council2, International Trademark Association3, Danish Space Research Institute4, University of Copenhagen5, European Southern Observatory6, University of Oulu7, University of A Coruña8, Michigan Technological University9, University of Nottingham10, University of Toronto11, Space Telescope Science Institute12, University of Amsterdam13, Goddard Space Flight Center14, Marshall Space Flight Center15, Clemson University16, University of California, Berkeley17, Lawrence Livermore National Laboratory18, University of Hertfordshire19, State University of New York System20, Steward Health Care System21
TL;DR: In this paper, the authors present optical follow up observations of the long GRB 001007 between 6.14 hours and 6.468 days after the event, showing that an unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light curve at t - to < 3.5 days, as found in other bursts.
Abstract: We present optical follow up observations of the long GRB 001007 between 6.14 hours and ~468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light curve at t - to < 3.5 days, as found in other bursts. Upper limits imposed by the LOTIS alerting system 6.14 hours after the gamma ray event provide tentative (1.2 sigma) evidence for a break in the optical light curve. The spectral index beta of the OA yields -1.24 +/- 0.57. These values may be explained both by several fireball jet models and by the cannonball model. Fireball spherical expansion models are not favoured. Late epoch deep imaging revealed the presence of a complex host galaxy system, composed of at least two objects located 1.2" (1.7 sigma) and 1.9" (2.7 sigma) from the afterglow position.
1 citations
01 Jan 2001
TL;DR: In this paper, the basic dynamics associated with a simple model of a dust particle interacting with a planetary gravitational field, solar radiation pressure and a constant magnetic field were examined, and the presence of global equilibrium points that are analogous to the Lagrangian equilibria of the circular restricted three-body problem was found.
Abstract: We examine the basic dynamics associated with a simple model of a dust particle interacting with a planetary gravitational field, solar radiation pressure and a constant magnetic field. We find the presence of global equilibrium points that are analogous to the Lagrangian equilibria of the circular restricted three-body problem. We focus on the nonlinear stability properties of the points in the case of a 1:2 resonance. These properties are analyzed by studying the phase flow on the reduced phase space after normalization.