In this document, we discuss practices related to the use of RDF-based
consensus vocabularies in the Virtual Observatory, that is the creation,
publication, maintenance, and consumption of hierarchical word lists
agreed upon within the IVOA. To cover the wide range of use cases
envisoned, we define different vocabulary types for informal knowledge
organisation on the one hand, and strict hierarchies of classes and
properties on the other. While the framework rests on the solid
foundations of W3C RDF, provisions are made to facilitate using IVOA
vocabularies without specific RDF tooling. Non-normative appendices
detail the current vocabulary-related tooling.
VODataService: a VOResource Schema Extension for Describing Collections and Services
Date:
21 Oct 2016 08:20:00
Publisher:
IVOA
Description:
VODataService refers to an XML encoding standard for a specialized extension of
the IVOA Resource Metadata that is useful for describing data collections and
the services that access them. It is defined as an extension of the core
resource metadata encoding standard known as VOResource [Plante et al. 2008]
using XML Schema. The specialized resource types defined by the VODataService
schema allow one to describe how the data underlying the resource cover the sky
as well as cover frequency and time. This coverage description leverages
heavily the Space-Time Coordinates (STC) standard schema [Rots 2007].
VODataService also enables detailed descriptions of tables that includes
information useful to the discovery of tabular data. It is intended that the
VODataService data types will be particularly useful in describing services
that support standard IVOA service protocols.
VO-DML: a consistent modeling language for IVOA data models
Date:
31 May 2018 09:00:00
Publisher:
IVOA
Description:
This document defines a standard modelling language, or meta-model, for
expressing data models in the IVOA. Adopting such a uniform language for all
models allows these to be used in a homogeneous manner and allows a
consistent definition of reuse of one model by another. The particular language
defined here includes a consistent identification mechanism for model which
allows these to be referenced in an explicit and uniform manner also from other
contexts, in particular from othe IVOA standard formats such as VOTable.
The language defined in this specification is named VO-DML (VO Data Modeling
Language). VO-DML is a conceptual modeling language that is agnostic of
serializations, or physical representations. This allows it to be designed to
fit as many purposes as possible. VO-DML is directly based on UML, and can be
seen as a particular representation of a UML2 Profile. VO-DML is restricted to
describing static data structures and from UML it only uses a subset of the
elements defined in its language for describing "Class Diagrams". Its concepts
can be easily mapped to equivalent data modelling concepts in other
representations such as relational databases, XML schemas and object-oriented
computer languages.
VO-DML has a representation as a simple XML dialect named VO-DML/XML
that must be used to provide the formal representation of a VO-MDL data model.
VO-DML/XML aims to be concise, explicit and easy to parse and use in code that
needs to interpret annotated data sets.
VO-DML as described in this document is an example of a domain specific
modeling language, where the domain here is defined as the set of data and
meta-data structures handled in the IVOA and Astronomy at large. VO-DML
provides a custom representation of such a language and as a side effect allows
the creation and use of standards compliant data models outside of the IVOA
standards context.
The ephemeris were produced by simulating the ejection of meteoroids
from the sunlit hemisphere of cometary nuclei, typically from 0 to 3
au, followed by the propagation of orbits of meteoroids in the Solar
System, taking into account the gravity of the Sun, the 8 planets,
Pluto, and the Moon, as well as the radiation pressure and the
Poynting-Robertson drag. Note that asteroid parent bodies were
considered as active (i.e. comet-like bodies) even if they are not
active today. The showers are predicted when a planet enters a large
enough set of meteoroids, at a distance less than typically 0.01 au.
See Vaubaillon J., Colas F., Jorda L. 2005 A new method to predict
meteor showers. I. Description of the model, Astronomy and
Astrophysics, Volume 439/2 p.751-760, as well as: Vaubaillon J. 2017 A
confidence index for forecasting of meteor showers, Planetary and
Space Science, Volume 143 p.78-82
New entries in the
`Virtual Observatory <http://www.ivoa.net>`_'s registry in RSS format;
this service lets you use a common "news aggregator" to learn of
services appearing in the VO in almost real time.
The data is taken from the VO registry by querying for new records
twice a day. New items are announced here for 30 days.
To subscribe to this feed, point your browser/news aggregator
to http://dc.g-vo.org/regrss.
If you can configure your client's update frequency, for this feed it
is sufficient to update every 12 hours -- it is only updated morining and
afternoon UTC.
New entries on this feed are also distributed `on the Fediverse`_. To
get notifications of new VO services, subscribe to `gavo@astrodon.social`_.
.. _gavo@astrodon.social:
.. _on the Fediverse: https://astrodon.social/@gavo
Space Research Centre of Polish Academy of Sciences
Description:
The VO HPSL datacenter is TAP end point. The Table Access Protocol
(TAP) lets you execute queries against our database tables, inspect
various metadata, and upload your own data. It is thus the VO's
premier way to access public data holdings.
Tables exposed through this endpoint include: columns, groups, key_columns, keys, schemas, tables from the tap_schema schema, epn_core from the rwcalerts schema, epn_core from the lofar_jupiter_raw schema, main from the arihip schema, epn_core from the lofar_jupiter schema, epn_core from the ionosondes schema, epn_core from the rwc_alerts schema, epn_core from the planetmongo schema.
The main goal of this work is to form a large, deep and representative sample of dwarf galaxies residing in voids of the nearby Universe. The formed sample is the basement for the comprehensive mass study of the galaxy content, their evolutionary status, clustering and dynamics with respect to their counterparts residing in more typical, denser regions and for study of void small-scale substructures. We present 25 voids over the entire sky within 25Mpc from the Local Group. They are defined as groups of lumped empty spheres bounded by `luminous' galaxies with the absolute K-band magnitudes brighter than -22.0. The identified void regions include the Local Void and other known nearby voids. The nearest nine voids occupy a substantial part of the Local Volume. Of the total number of 6792 cataloged galaxies in the considered volume, 1354 objects fall into 25 nearby voids. Of this general void galaxy sample, we separate the sub-sample of 'inner' void galaxies, residing deeper in voids, with distances to the nearest luminous galaxy DNN>2.0Mpc. The 'inner' galaxy sample includes 1088 objects, mostly dwarfs with MB distribution peaked near -15.0 and extending down to -7.5mag. Of them, 195 fall in the Local Volume (space within R=11Mpc). We present the general statistical properties of this Nearby Void Galaxy sample and discuss the issues related to the sample content and the prospects of its use.
We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6{mu}m and 4.5{mu}m Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from M_B_=-15.5 to -20, while at the 3.6{mu}m band their magnitudes range from M_3.6_=-18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3x10^10^M_{sun}_. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sersic indices are nearly all smaller than n=2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.
This service lets VO data publishers assign Digital Object Identifiers
to their services, greatly enhancing their citability. Since
technically, the DOI references the registry record, this service can
only be used on properly registered services.
