Developmentsof theopenclusterdatabase WEBDA

Developments of the open cluster databaseWEBDA

Martin Netopil, Ernst Paunzen, Christian StützInst. of Astronomy, Univ. Vienna

JENAM 2010, Lisbon, 10th Sept 2010

Developments of the open cluster database WEBDA

what is WEBDA?

initiated by J.C. Mermilliod in 1987 as BDA (Base Données Amas),1997 the WWW version was made public – WEBDAIn Oct. 2005 our group (head Ernst Paunzen) has inherited the duties.

=> http://www.univie.ac.at/webda

the database is intended to provide a reliable picture of the available data and knowledge on open clusters and to offer a wide access to the existing observations.

numerous data are only available within WEBDA => „to go hunting“ is a main task

within a cluster, an internal numbering system allows to compare different datasets

WEBDA does not claim anything – we just try to compile datait has to be up to the user to decide what is useful, wrong etc.


what is WEBDA?

the current layout …


current content


current content

In total 653 clusters observed in the „major“ photometric systems (#stars >= 20)

uvby: pe + CCD mergedbyHα: McSwain et al. 2005

If considering also ASCC(Kharchenko et al. 2001/5)=> 900 clusters „covered“


increase of data

number of clusters and starsin the photometric system UBVRI

use of WFIs and larger telescopesresults in increase of measured starsand magnitude limit


increase of data

restricted possibilities to fit isochrones are already available, but …

… sometimes, the plotting routines are notreally sufficient anymore for large datasets


new plotting routines

more flexibility torestrict the data to the„interesting“ region of theCMD

also restriction to indicatedareas (diameter) in preparation

given errors can bedisplayed for all cluster parameters



also a more user-friendlychart plot to pick and display regions



also the capabilityto compare different datasets will beincreased

e.g. linear fits will bederived automatically


limitation of current content - coordinates

about 40% of all objects have no J2000 coordinates!

~120 already investigated clusters haveno single entry of equatorial coordinates

unfortunately, still several investigationsprovide only X/Y coordinates!

this makes a systematic cross match with all-sky data impossible.

with the new „release“ we want to close this gap

transformation [X,Y] <=> [alpha,delta] for all included objects

all stars will be searchable via coordinates


limitation of current content - coordinates

example of a published datasetcausing „troubles“

if such things happen within a „manual“ reduction …

how can complete automaticpipelines solve such problems?


limitation of current content - photometry

all included studies claim to represent „standardphotometry“

different clusters, different studies …

WEBDA reveals „problems“ in photometry easily.

in several studies a comparison with literature valuesis often underrepresented.

unfortunately, only an excerpt of „worst cases“ …


individual studies sky surveys

most recent sky surveys are aimed at fainter magnitudes

IPHAS data (AB scale)of NGC 7062 (~ 2 kpc)

data of up to 4 framesaveraged


individual studies sky surveys

in some cases a combination with individual studies is essential

IPHAS data (AB scale)of NGC 7062 (~ 2 kpc)

+ transformed VRI photometry for brightercluster stars(relations by Jordi et al. 2006)∆(r-i)~0.02mag

log t =8.7 (SDSS Isos)


future extension + wishes

extensionassociations, star forming regionssystematic inclusion of survey data

wishes to community to improve WEBDAself-control during data reductionindication of identified objects from other publicationsprovide also equatorial coordinates

more FEEDBACK! missing data, wrong identifications, etc.everything is helpful …

Documents

Developmentsof theopenclusterdatabase WEBDA