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.
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.