Dear Sebastian and other colleagues, The magnitude V=5.684 for 18 Tau is also confirmed by transformed Hipparcos photometry - see Harmanec 1998 A&A 335, 173 - Fig. 5 on p. 175 and by calibrated all-sky photometry from San Padro Martir: V=5.683+/-0.008. Hrvoje Bozic promised to obtain UBV photometry of HD 23873 as soon as weather at Hvar will permit it. We shall then keep you informed. Best wishes, Petr Harmanec