Information on Service 'UCD Query'

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The Unified Content Descriptor (UCD) is a formal vocabulary astronomical data that is controlled by the International Virtual Observatory Alliance (IVOA). The vocabulary is restricted in order to avoid proliferation of terms and synonyms, and controlled in order to avoid ambiguities as far as possible. It is intended to be flexible, so that it is understandable to both humans and computers. UCDs describe astronomical quantities, and they are built by combining words from the controlled vocabulary.

For a list of all services and tables belonging to this service's resource, see Information on resource 'UCD Query'

Service Documentation

The Unified Content Descriptor (UCD) is a formal vocabulary for astronomical data that is controlled by the International Virtual Observatory Alliance (IVOA). The vocabulary is restricted in order to avoid proliferation of terms and synonyms, and controlled in order to avoid ambiguities as far as possible. It is intended to be flexible, so that it is understandable to both humans and computers. UCDs describe astronomical quantities, and they are built by combining words from the controlled vocabulary.

A UCD does not define the units nor the name of a quantity, but rather "what sort of quantity is this?"; for example phys.temperature represents a temperature, without implying a particular unit.

It would be possible to describe astronomical data quantities in a natural language such as English or Hungarian or Uzbek; however, it would be very difficult to expect a machine to 'understand' it in any sense. At the opposite extreme, there is an attempt within the IVOA to describe astronomical data in terms of a hierarchical data model, so that there is a place for everything, and everything is in its place. The UCD vocabulary falls between these extremes, and is intended to be understandable to both humans and computers.

Overview

You can access this service using:

This service is published as follows:

local means it is listed on our front page, ivo_managed means it has a record in the VO registry, gavo means it is within GAVO's service registry.

Input Fields

The following fields are available to provide input to the service (with some renderers, some of these fields may be unavailable):

NameTable Head DescriptionUnitUCD
ucd UCD Unified Content Descriptors from IVOA N/A N/A
ucd_desc Description. The simple explaination of UCD N/A N/A

Default Output Fields

The following fields are contained in the output by default. More fields may be available for selection; these would be given below in the VOTable output fields.

NameTable Head DescriptionUnitUCD
ucd UCD Unified Content Descriptors from IVOA N/A N/A
ucd_desc Description. The simple explaination of UCD N/A N/A

VOTable Output Fields

The following fields are available in VOTable output. The verbosity level is a number intended to represent the relative importance of the field on a scale of 1 to 30. The services take a VERB argument. A field is included in the output if their verbosity level is less or equal VERB*10.

NameTable Head DescriptionUnitUCD Verb. Level
ucd UCD Unified Content Descriptors from IVOA N/A N/A 20
ucd_desc Description. The simple explaination of UCD N/A N/A 20

Copyright, License, Acknowledgements

The data List of UCD obtained from ucd1p-words-20070402.txt (http://cdsweb.u-strasbg.fr/UCD/).

VOResource XML (that's something exclusively for VO nerds)