SIMBAD references

European South Observatory Very Large Telescope observations using FORS 2 in spectropolarimetric mode reveal the presence of a variable magnetic field and spectral variability in the Of?p star CPD-28 2561 Only five Galactic Of?p stars are presently known: HD 108, NGC 1624-2, CPD-28 2561, HD 148937, and HD 191612. After our previous detection of a magnetic field in the Of?p star HD 148937 using FORS 1 at the VLT, it is the second Of?p star with a detected magnetic field of the order of a few hundred Gauss. The obtained low-resolution FORS 2 polarimetric spectra allowed us to detect clear variability of several hydrogen and helium lines on a rather short time scale.