2. The observational material

The material has been collected during a 23-night observing run at La Silla with the 70 cm telescope of the Geneva Observatory equipped with the standard Geneva photometer (Burnet & Rufener 1979). Each star was observed about once per night in the seven-colour Geneva photometric system (U, B, V, B1, B2, V1, G). Although the absolute photometry is of high quality, we observed Geneva standards as comparison or check stars in the vicinity of each programme stars.

Aside from the seven magnitudes we considered the usual color indices of the Geneva system. Moreover, we added the intermediate-band index B1-V1. Never used in Geneva photometry, this index is the only missing linear combination of "narrow''-band data. We included it because it displays the largest amplitude of variations for several stars.

Data relative to the programme stars are given in Table 1 (click here). Comparison stars are also listed, as is the number of useful observations. The "Rns'' number refers to the catalogue of Ap and Am stars by Renson et al. (1991). One additional star, HD 190422 = HR 7674, had been observed as a comparison and found to be variable.

 

HD Rns V sp. type comparison(s)

8717¹ 2100 8.358 A4 Cr 9906 24

9050 2194 8.952 A0 EuSr 8589 25

9529¹ 2310 9.164 F6 Sr 14287 25

187039 51550 9.396 A2 Si 162515 & 187923 18

187752 51800 8.503 B9 Si 162515 & 187923 18

188309 52010 9.968 A2 Si 162515 & 187923 18

191439 53340 8.887 B9 CrEuSr 29

191857¹ 53500 8.805 A1 Si 162515 & 187923 16

355163 53540 9.628 B9 Si 162515 & 187923 15

192674 53730 7.552 B9 CrEuSr 29

192687 53770 9.225 A1 Si 162515 & 187923 18

194750 54310 8.876 A0 SrSiCr 199288 26

195112 54390 8.847 B9 EuCrSr 199288 28

200199¹ 55760 6.998 A1 Cr 201901 22

200623 55940 9.066 A2 SrEuCr 201901 21

204367¹ 56910 7.805 A0 SrEuCr 201901 21

207259 57690 8.862 A0 EuCrSr 203608 24

216965 59900 8.317 F0p 218045 19

222561 61020 8.519 A4p 222847 24

222638 61030 8.662 A0 SrEuCr 212330 26

222925 61140 9.005 F8 SrEu 212330 26

Table 1: Stars analyzed. Rns stands for the Catalogue Général des Etoiles Ap et Am by Renson (Renson et al. 1991). The V magnitude is an average derived from our Geneva measurements. The spectral type is from Renson's catalogue. The HD number of the comparison(s) is given. N is the number of useful measurements

Ap nature given as uncertain in Renson's catalogue.