Abstract
The systematic study of some HADS stars, recognized as variables for decades, has allowed us to provide data on their secular variations through O-C analysis. However, some of the data have large gaps without observations. This is our motivation for continuously observing these stars as part of the research carried out by the "Grupo de Astronomía Observacional del Observatorio de Tonantzintla" (GAOOT). This article is our third compilation of times of maxima for pulsating stars. These observations have been carried out at the Observatorio Astronómico Nacional de Tonantzintla (TNT) and San Pedro Mártir (SPM), México and for the first time we also present data from the Complejo Astronómico de Cota Cota, Bolivia (Universidad Mayor de San Andrés) and the Observatorio Astronómico Centroamericano de Suyapa, Honduras (Universidad Nacional Autónoma de Honduras).
