The most important contribution of this paper is that, along with the new photometric data presented, a comparative analysis of the computing codes for period analysis was carried out. It has been proven that the results of the codes practically show the same results. A compilation of the different frequency sets for each star has been done and for a few of them it is clear that it is not easy to derive a final set of frequencies provided it exists. In particular for KW 204 the amazing result is that with only one frequency it is possible to describe all the published observations of this star discarding all other sets. This might prove that many frequencies associated with some stars could be due merely to the poorness of the data either because of poor quality nights, pseudoconstant stars or merely because the data has not been properly reduced or analyzed. It is unnecessary at this stage to encourage well coordinated campaigns for each star before definite frequencies sets are assigned in order to describe their pulsational nature.
Acknowledgements
This paper was possible to the partial funds provided by Conacyt through grants 3925E and the cooperation with CSIC, E130-3059, and the Hungarian Academy of Sciences. Special thanks to the staff of the observatories who made the observations possible. Typing and proofreading were done by J. Orta and J. Miller. Two of us, JHP and RP would like to thank the hospitality of the Konkoly Observatory, Hungary and JHP, RP, MAH and CdC that of the Instituto de Astrofısica de Andalucıa, Spain. This research has made use of the Simbad databases operated at CDS, Strasbourg, France. Special thanks to referee, Dr. J.C. Mermilliod, whose comments and suggestions improved this paper.