MultiPurpose Metadata Repository for a Real

1
Multi-Purpose Metadata Repository for a Real
Virtual Observatory
Metadata Model The basic model is made of three
classes RegCommon, RegService, and RegData.
Depending on the type of the attribute, further
modeling has been performed. In order to better
express entities, the construction of a
dictionary of internal terms has been
initiated. To clarify the model the following
example is presented how to map the seeing
attribute and its corresponding error.

• M. C. Leoni1, M. Dolensky1, A. Micol2, P.
  Padovani1, P. Rosati1, A. Wicenec1

1 European Southern Observatory, Germany
2 Space Telescope European Coordinating
Facility, Germany
Example name value unit
UCD Seeing
0.5 arcsec instr.obsty.seeing Seeing
Error 0.05 arcsec
stat.errorinstr.obsty.seeing The seeing
attribute part of the SpatialInfo class is
defined as a ValueWithUnit type. In this case,
the value attribute will be 0.5, while unit is
arcsec. Same for the seeing error being a
ValueWithUnit, it will have a value of 0.05, and
again arcsec as unit. The other attribute of the
VOUnit class, i.e. the ucd field, will be filled
with instr.obsty.seeing and stat.errorinstr.ob
sty.seeing, for the seeing and the Seeing
Error respectively. On the other end, the
coordinates will be represented following the
model defined in the Space-Time Metadata for the
Virtual Observatory document 5.
Abstract This work presents the study and design
of the ESO meta data repository. The process
followed for gathering the scientific
requirements and the structure of the database
used as a container for the meta data will result
in a new VO compatible archive interface by
2006. ESO's new Science Archive Facility (SAF)
will be built upon a meta data repository which
will satisfy both the needs specific to a real
observatory as well as new requirements for the
virtual observatory derived from IVOA
interoperability standards, such as registry and
access protocols.
Advanced 2,3 Data Products
Data Sets
Ingestion Engine 4
User
Archive Interface 1
IVOA Protocols
Portals
IDs
References Links 1 Delmotte N. et al., ESO
Science Archive Interfaces, ADASS XV 2 Retzlaff
J. et al., ESO Advanced Data Products for the VO,
ADASS XV 3 Rite C. et al., User Interface for
ESO ADP Image Reduction Pipeline, ADASS XV 4
Slijkhuis R. et al., Feeding VO Data Products
into the Archive, ADASS XV 5 IVOA Documents,
http//ivoa.net/Documents
Data
Meta data
Harvesting
VO Registries

• Repository Scope
• The scope of the meta data repository is to
• register ESO/ECF observational data and existing
  resources
• support characterization and ingestion of
  external data collections based on ESO/ECF
  observations
• implement IVOA local publishing registry
• support the Science Archive (see 1 for more
  details).
• The repository is there to store meta data about
  ESO and HST data products in such a way that the
  various concepts introduced by data modellers and
  registry experts can be supported. It will be
  possible to build a registry harvesting interface
  against it as well as other interfaces (e.g. SIA,
  SSA). Ingesting data products will therefore be
  more than registering them in the IVOA sense.

Virtual Observatory Systems Department
2

• Collecting Requirements
• The hardest single part of building a software
  system is deciding precisely what to build.
  (Fred Brooks)
• Capture user requirements is a tough though
  basic - activity. In this case the user is the
  astronomer interrogating the archive in search of
  useful information.
• Metadata requirements for the ESO/ECF Science
  Archive Facility entail
• support of the SAF user interface
• ability to resolve queries stemming from IVOA
  protocols and services
• a harvesting interface enabling VO registries to
  mirror and propagate public resource metadata.

IVOA Standards Compliancy with emerging IVOA
standards 5 is fundamental to achieve
interoperability with other VOs. Most of the
documents are still in a transitory stage,
nevertheless they have been taken into account at
design time. Future refinements may be required
in order to follow the evolution of the
standards, thus reflecting changes on the meta
data repository. This will likely be only a
re-mapping of the basic meta data. Note colour
gradations indicate different maturity level
reached by standards. Legenda DM Data
Model ID Identifiers RM Resource Metadata
SIA Simple Image Access Protocol SSA Simple
Spectrum Access Protocol STC Space-Time
Coordinate UCD Unified Content Descriptors
RegCommon

• title String
• identifier VOID
• publisher VOPublisher
• subject String
• description String
• referenceURL URL
• type ResourceType
• releaseDate AbsoluteTime
• expirationDate AbsoluteTime
• publicFlag boolean FALSE
• searchableFlag boolean TRUE
• updated AbsoluteTime
• techCheck String

RegData

• proposalID String
• targetName String
• typeOfObservation String
• techniqueOfObservation String
• spatialInfo SpatialInfo
• spectralInfo SpectralInfo
• zpInfo ZPInfo
• instrument PlatformType
• opticalElements SignalModifierType 0..
• detectorMode String
• format String
• processingType SignalModifierType 0..
• comments String
• temporalInfo TemporalInfo
• numberOfFrames int
• effectiveGain ValueWithUnit
• scientificValidationStatus String
• paperReference URI 0..
• fieldOfView FOV

SpatialInfo

• - spatialCorners Coordinates 1..
• numbersOfBins int
• binSize ValueWithUnit
• seeing ValueWithUnit
• seeingError ValueWithUnit

Seeing
Seeing Error
RegService
Uncertainty

• - interfaceURL URL
• baseURL URL
• httpResultsMimeType String
• standardURI URI
• standardURL URL
• maxSearchRadius int
• relationship String
• relationshipID VOID

ValueWithUnit
- type String - value ValueWithUnit 1..
Value
- unit VOUnit 1.. - value Value
VOUnit
Unit
ComplexWithUnit
DoubleWithUnit
IntegerWithUnit
- unit char
- ucd UcdEnumeration
- value int
- value double
- value DoubleWithUnit2
instr.obsty.seeing
(e.g. RA and DEC)
Coordinates
Unfied Content Descriptors
STC
stat.errorinstr.obsty.seeing