[CATALOGUE] Source Catalogue DM

Pedro Osuna Pedro.Osuna at sciops.esa.int
Wed Apr 27 07:32:44 PDT 2005 

Dear all,

Matteo Guainazzi (ESA-VO and XMM-Newton Archive Scientist) has compiled
information on several source catalogues on different wavelengths and
together with Jesus Salgado an myself we have compiled a tentative
Source Catalogue Data Model, that would plug in the general Catalogue 
Data Model that we discussed back in Pune.

We attach a UML diagram of the model to serve as a starting point for
discussion. 

You will see in the model that certain of the Source specific
characteristics that Matteo has identified correspond to other Data
Models that are being worked by other sub-groups.

With my Catalogue DM coordinator's hat, could I ask Jonathan (for the
SED) and Alberto (for the Observation/Characterisation) to cross check
which of the relevant items boxed in the diagram correspond to items in
their respective models? And in case they are not there, would it be
possible to add them?

A small description -by Matteo- of each of the physical attributes 
in the model follows together with a description by Jesus and myself 
on the model itself. 
The attributes' types in the model have been put for reference and 
should not be taken as definitive. 

Please do have a look to the Model and send your comments; this is the
only way to have flexible and powerful Data Models fulfilling all the
needs.

Feel free to send comments to the whole Catalogue dm group
(dm-catalog at ivoa.net) or, in case you send them to the general DM group
, do it with a subject containing the word [CATALOGUE] so that the rest 
of DM-ers can filter properly.


Cheers,
P.


++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

UML diagram
===========
Objects:
-------
Source
------
We have decided to have a quite general and big-ish object called Source
with as much information as possible inside. Smaller or finer grain
could have been obtained by separating the attributes on the Source
object to smaller objects. However, in view of the fact that the source
is just but one item in the possible "Catalogue entries", we thought
that there are already too many subdivisions, and hence decided to build
only one.

Certain attributes of the Source object will, obviously, only apply to
some sources (a clear example being, e.g., the visualAlbedo). 

The idea of the "id" is to leave a place for specific IDs for specific
projects. The standard naming for the sources should be filled in (if
known) on the SIMBADName and IAUName.

Wherever STC appears, it makes reference to certain item in the Space
Time Coordinate Data Model from Arnold.

Orbit is obviously only related to objects following an orbit, like
binary systems. In this case, a specific object has been isolated as it
might become quite big if we decide to add more specific attributes to
the orbits of the objects (some of which are very well known). In this
case, we have doubted whether any effort exists in the Data Model groups
to describe orbits in general (Jonathan: would it need to be considered
separately?).


Morphology
----------
Morphology has been separated to account for possible extended source
information. In the case that a Source is identified to be of a certain
type (for example, a Galaxy) this Galaxy model should extend the
Morphology and add more specific attributes to it (in the case of a
Galaxy, for example, whtehr the galaxy is Sprial SB, or Sa, elliptical,
irregular, etc.).

Orbit
-----
We have decided, as mentioned above, to isolate this item as it might
grow easily if we decide to give very specific information for orbits,
some of which might be very well known. For the time being, we give only
a reduced set of attributes.


STC
---
Relevant items to the Source model are specified there. Arnold should
revise their validity.

SED
---
Jonathan should revise which of the items inside this box are present in
the SED, and in case they are not, decide if they can be created.
Otherwise, we might want to create an isolated object for this.

Observation
-----------
Alberto should revise this bit and give information (as above).


AGN
---
This is not an object as such. It is a place holder for any possbile
AstronomicalObjects that we might want to describe in the future. We
agreed in the past that in many catalogues, the type of source is either
unknown or irrelevant, therefore not neededing an identification.
However, other catalogues will consist, e.g., of only galaxies, for
example. In this case, a Galaxy model should exist to which we could
point the "type" attribute of "Source". This AGN object represents one
of those future objects.

 
Physical Description of attributes
==================================

- "id":		Name of the source 

- "IAUName": 	IAU name of the source

- "SIMDABName": SIMBAD name of the identified counterpart

- "type": 	Source class. It may reflect a standard object
		classification as in e.g.: 	http://simbad.u-strasbg.fr/guide/chF.htx

- "coordinates": The sky coordinates of the source

- "frequency": 	The frequency, at which the flux/magnitude/count ("flux"
  hereafter) measurements in the catalogue were taken

- "snr": Source significance in terms of signal-to-noise ratio

- "detectionProbability": Source detection probability

- "distance": Distance of the source from "distanceOrigin". The
cosmological redshift is a possible instantiation of this attribute

- "distanceDeterminationMethod": Method employed to determine
"distance". "Spectra", "Photometric", "Parallax" are possible values of
this attribute

- "distanceOrigin": Origin from which "distance" is being measured

- "properMotion": the source proper motion on the sky vault

- "radialVelocity": the radial component of the source velocity

- "varAmplitude": the amplitude of the "varType" amplitude variability.
It can be expressed either in physical absolute, r.m.s, or in fractional
units

- "varPeriod": the type of source variability: "Periodic",
"Quasi-periodic",  "Burst of Type I", "Aperiodic" are possible values of
this attribute

- "polarisatinDegree": degree of source polarization

- "polarisationAngle": positional angle of the source polarization

- "visualAlbedo": source visual albedo

- "minorDiameter": size of the minor diameter of the source

- "majorDiameter': size of the major diameter of the source

- "inclination": angle between the line-of-sight to the source and the
  normal of the main source symmetry plane

- "positionAngle": apparent position angle of the source on the sky
vault

- "stellarityIndex": parameter ranging from 0 (galaxy) to 1 (star),
related to the probability that a given object is extended or point-like

- "form": string describing the geometrical shape and/or symmetry of the
   source. "Boxy", "Patchy", "Ring", are possible values for this 
attribute

- "perihelion": minimum distance from a reference point along the orbit

- "perihelionTime": time of the source passing through the orbit
perihelion

- "afelion": maximum distance from a reference point along the orbit

- "inclination": angle between the line-of-sight to the source and the
  normal to the plane containing the orbit

- "eccentricity": fraction of the distance along the semi-major axis at
which the focus lies (e=c/a, where c is the distance from the center of
the conic section to the focus and a is the semi-major axis)

- "positionAngle": apparent position angle of the orbit on the sky vault

- "period": orbital period



-- 
Pedro Osuna Alcalaya

 
Software Engineer
Science Archive Team
European Space Astronomy Centre
(ESAC/ESA)
e-mail: Pedro.Osuna at esa.int
Tel + 34 91 8131314
---------------------------------                                                                                
European Space Astronomy Centre
European Space Agency
P.O. Box 50727
E-28080 Villafranca del Castillo
MADRID - SPAIN
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