4,726 research outputs found
THE USE OF STANDARDS IN HELIO
HELIO [8] is a project funded under the FP7 program for the discovery and analysis of data for heliophysics. During its development, standards and common frameworks were adopted in three main areas of the project: query services, processing services, and the security infrastructure. After a ïŹrst, proprietary implementation of the security service, it was suggested moving it to a standard security framework to simplify the enforcement of security on the diïŹerent sites. As the HELIO front end is built with Spring and the TAVERNA server (HELIO workïŹow engine) has a security framework compatible with Spring, it has been decided to move the CIS in Spring security [2]. HELIO has two diïŹerent processing services: one is a generic processing service called HELIO Processing Services (HPS), the other is called Context Service (CTX) and it runs speciïŹc IDL procedures. The CTX implements the UWS [4] interface from the IVOA [5], a standard interface for job submission used in the helio and astro-physics community. In its ïŹnal release, the HPS will expose an UWS compliant interface. Finally, some of the HELIO services perform queries, to simplify the implementation and usage of this services a single query interface (the HELIO Query Interface) has been designed for all these services. The use of these solutions for security, execution, and query allows for easier implementation of the original HELIO architecture and for a simpler deployment of the services
The Optical Velocity of the Antlia Dwarf Galaxy
We present the results of a VLT observing program carried out in service mode
using FORS1 on ANTU in Long Slit mode to determine the optical velocities of
nearby low surface brightness galaxies. Outlying Local Group galaxies are of
paramount importance in placing constraints the dynamics and thus on both the
age and the total mass of the Local Group. Optical velocities are also
necessary to determine if the observations of HI gas in and around these
systems are the result of gas associated with these galaxies or a chance
superposition with high velocity HI clouds or the Magellanic Stream. The data
were of sufficient signal-to-noise to obtain a reliable result in one of the
galaxies we observed - Antlia - for which we have found an optical
helio-centric radial velocity of 351 15 km/s.Comment: 11 pages, 4 figures, 5 tables MNRAS, in pres
The OSACA Database and a Kinematic Analysis of Stars in the Solar Neighborhood
We transformed radial velocities compiled from more than 1400 published
sources, including the Geneva--Copenhagen survey of the solar neighborhood
(CORAVEL-CfA), into a uniform system based on the radial velocities of 854
standard stars in our list. This enabled us to calculate the average weighted
radial velocities for more than 25~000 HIPPARCOS stars located in the local
Galactic spiral arm (Orion arm) with a median error of +-1 km/s. We use these
radial velocities together with the stars' coordinates, parallaxes, and proper
motions to determine their Galactic coordinates and space velocities. These
quantities, along with other parameters of the stars, are available from the
continuously updated Orion Spiral Arm CAtalogue (OSACA) and the associated
database. We perform a kinematic analysis of the stars by applying an
Ogorodnikov-Milne model to the OSACA data. The kinematics of the nearest single
and multiple main-sequence stars differ substantially. We used distant
(r\approx 0.2 kpc) stars of mixed spectral composition to estimate the angular
velocity of the Galactic rotation -25.7+-1.2 km/s/kpc, and the vertex
deviation,l=13+-2 degrees, and detect a negative K effect. This negative K
effect is most conspicuous in the motion of A0-A5 giants, and is equal to
K=-13.1+-2.0 km/s/kpc.Comment: 16 pages, 8 figure
Planetary Science Virtual Observatory architecture
In the framework of the Europlanet-RI program, a prototype of Virtual
Observatory dedicated to Planetary Science was defined. Most of the activity
was dedicated to the elaboration of standards to retrieve and visualize data in
this field, and to provide light procedures to teams who wish to contribute
with on-line data services. The architecture of this VO system and selected
solutions are presented here, together with existing demonstrators
An Optical Velocity for the Phoenix Dwarf Galaxy
We present the results of a VLT observing program carried out in service mode
using FORS1 on ANTU in Long Slit mode to determine the optical velocities of
nearby low surface brightness galaxies. As part of our program of service
observations we obtained long-slit spectra of several members of the Phoenix
dwarf galaxy from which we derive an optical helio-centric radial velocity of
-13 +/- 9km/s. This agrees very well with the velocity of the most promising of
the HI clouds seen around Phoenix, which has a helio-centric velocity of -23
km/s, but is significantly different to the recently published optical
heliocentric velocity of Phoenix of -52 +/- 6 km/s of Gallart et al. (2001).Comment: Aceepted for publication in MNRA
Requirements for regional short-haul air service and the definition of a flight program to determine neighborhood reactions to small transport aircraft
An evaluation of the current status and future requirements of an intraregional short haul air service is given. A brief definition of the different types of short haul air service is given. This is followed by a historical review of previous attempts to develop short haul air service in high density urban areas and an assessment of the current status. The requirements for intraregional air service, the need for economic and environmental viability and the need for a flight research program are defined. A detailed outline of a research program that would determine urban community reaction to frequent operations of small transport aircraft is also given. Both the operation of such an experiment in a specific region (San Francisco Bay area) and the necessary design modifications of an existing fixed wing aircraft which could be used in the experiment are established. An estimate is made of overall program costs
Spectroscopy of Giant Stars in the Pyxis Globular Cluster
The Pyxis globular cluster is a recently discovered globular cluster that
lies in the outer halo (R_{gc} ~ 40 kpc) of the Milky Way. Pyxis lies along one
of the proposed orbital planes of the Large Magellanic Cloud (LMC), and it has
been proposed to be a detached LMC globular cluster captured by the Milky Way.
We present the first measurement of the radial velocity of the Pyxis globular
cluster based on spectra of six Pyxis giant stars. The mean heliocentric radial
velocity is ~ 36 km/sec, and the corresponding velocity of Pyxis with respect
to a stationary observer at the position of the Sun is ~ -191 km/sec. This
radial velocity is a large enough fraction of the cluster's expected total
space velocity, assuming that it is bound to the Milky Way, that it allows
strict limits to be placed on the range of permissible transverse velocities
that Pyxis could have in the case that it still shares or nearly shares an
orbital pole with the LMC. We can rule out that Pyxis is on a near circular
orbit if it is Magellanic debris, but we cannot rule out an eccentric orbit
associated with the LMC. We have calculated the range of allowed proper motions
for the Pyxis globular cluster that result in the cluster having an orbital
pole within 15 degrees of the present orbital pole of the LMC and that are
consistent with our measured radial velocity, but verification of the tidal
capture hypothesis must await proper motion measurement from the Space
Interferometry Mission or HST. A spectroscopic metallicity estimate of [Fe/H] =
-1.4 +/- 0.1 is determined for Pyxis from several spectra of its brightest
giant; this is consistent with photometric determinations of the cluster
metallicity from isochrone fitting.Comment: 22 pages, 5 figures, aaspp4 style, accepted for publication in
October, 2000 issue of the PAS
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