The Eggen uvby photometric system

Basic Reference

Eggen O.J. 1976, Publ. Astron. Soc. Pacific 88, 732


In four-color, intermediate-band photometry of late-type stars, difficulty has been experienced in reproducing the Strömgren system defined by standard stars by Crawford and Barnes. The difficulty is believed to be connected with the fact that an international bulk of order for filters has produced a considerably narrower v filter than that used in the original observations of standard stars. Because of this difficulty a new system has been defined which is characterized by (b-y) = (b-y)Strömgren, M1 = m1(Strömgren) for (b-y) < 0.30 and C1 = c1(Strömgren) for (b-y) < 0.20. The use of M1 as a metal-abundance parameter is demonstrated with Hyades-cluster and group stars and members of the Arcturus group, as well as some very metal-weak subdwarfs.


Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

Ve, b-y, M1, C1




In the course of a systematic comparison of photometric data, a number of problems have been found, but could not be solved. Generally the data associated with a star identification are not in agreement with those from other systems, usually the UBV, uvby and Geneva systems.


A number of printing errors have been found in tables.

Please, send your commentsto
Last update: 13 September 2002