2 Program stars

The catalogue of Ap and Am stars by Renson (1991) was used to search for entries in the HVA. 293 objects were found in the first part (periodic variables) whereas 106 objects are included in the second part (unsolved variables). The latter will be discussed in a forthcoming paper. From these 293 objects, we excluded 33 because:

• Twelve are well known $\delta$Scuti or $\delta$Delphini stars and no "classical'' CP stars, these are: HD 2628, HD 67523, HD 67911, HD 93137, HD 101696, HD 106384, HD 115604, HD 172748, HD 185139, HD 197461, HD 201707 and HD 213534.
• Eighteen have no period due to poor phase coverage or other reasons, these are: HD 5303, HD 30050, HD 34364, HD 36412, HD 40183, HD 82829, HD 89143, HD 113158, HD 128661, HD 156965, HD 161321, HD 178001, HD 185257, HD 187474, HD 205234, HD 209147, HD 215661 and HD 216429.
• Three are very probably no CP stars since the exhibit a non-peculiar $\Delta a$ index despite their B-type characteristics, these are: HD 24587 (B6; $\Delta a$=-1), HD 38602 (B9Si; $\Delta a$=-2) and HD 66546 (B7Si; $\Delta a$=-6).

From the remaining 260 program stars, half have already been included in the catalogue of observed periods of Ap and Bp stars by Catalano & Renson (1997). We will discuss only those cases where the period given in this catalogue does not agree (within the error bars) with HVA. In the following we will concentrate on the newly discovered variable CP stars. The fraction of rotationally variable CP stars constitutes an increase of about 20 percent related to the catalogue of Catalano & Renson.