2006A&A...455..303J

We search for photometric variability in chemically peculiar A type stars in the northern hemisphere. High-speed photometric observations of Ap and Am star candidates have been carried out from ARIES (Manora Peak, Nainital) using a three-channel fast photometer attached to the ARIES 104-cm Sampurnanand telescope. This paper presents three new variables: HD113878, HD118660 and HD207561. During the time span of the survey (1999 December to 2004 January) pulsations of the δSct type were also found for the two evolved Am stars HD102480 and HD98851, as reported in Joshi et al. (2002, 2002, Commun. Asteroseismol., 142, 50; 2003MNRAS.344..431J). Additionally, we present 140 null results of the survey for this time span. The star HD113878 pulsates with a period of 2.31h, which is typical of δSct stars. HD118660 exhibits multi-periodic variability with a prominent period of nearly 1h. These periods need to be investigated and make HD118660 a particularly interesting target for further observations. For HD207561, a star classified as Am, a probable pulsation with a period of 6min was found in the light curves obtained on two consecutive nights. Both HD102480 and HD98851 exhibit unusual alternating high and low amplitude maxima, with a period ratio of 2:1. The analysis of the null results confirms the photometric quality of the Nainital site.