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About the project

Cepheid variable stars play a fundamental role in astronomy because they are standard candles in calibrating the cosmic distance scale via the period-luminosity relationship. As of early 2019, Cepheids have been discovered in 96 galaxies beyond the Milky Way. The total number of known Cepheid variable stars exceeds 19000 (not counting the newly discovered ones announced in Gaia DR2).

The aim of the online data base maintained at the web site of the Konkoly Observatory is to provide an easy access to the available photometric data on individual extragalactic Cepheids and to facilitate statistical studies on Cepheid variables known in external galaxies. Stars belonging to any type of Cepheid variables (classical, anomalous, Type II) have been included in this data base. Suspected variables and ambiguously identifiable Cepheids have remained, however, out of consideration.
The construction of the data base is in progress and has not been finished yet. Data on variables in galaxies hosting largest numbers of known Cepheids (Small Magellanic Cloud, Large Magellanic Cloud, M31, etc.) will be uploaded at a later phase of the project. Until now we have 5611 cepheids in 85 galaxies.

The structure of this web-site

The table in the Statistics menu lists the number of known Cepheids in the individual galaxies. The detailed data on Cepheids are accessible by clicking on the name of the host galaxy. The Database menu offers the list of the galaxies hosting Cepheids. Selecting a given galaxy, then clicking on the OK button, a table listing the relevant information (coordinates, pulsation period, mean magnitudes in various photometric bands, remarks) is shown. The name of the galaxy at the upper right corner is linked to the NASA/IPAC Extragalactic Database. Clicking on the ID of the Cepheid brings the SIMBAD web-page of the given star on screen. A list of research papers publishing photometric data on the Cepheids in the given galaxy is found below the table. This bibliographic list is linked to the ADS.
Remarks and suggestions are welcome in order to improve the structure and information content. Contact address is: szabados at konkoly.hu.

Acknowledgments

Technical help from Nikolett Szalai, Andras Holl and Mihaly Varadi is gratefully acknowledged. Construction and maintenance of this data base has been supported by the ESTEC Contract No.4000106398/12/NL/KML.