SIMBAD references

The eye can distinguish brightness differences as small as ± 0.1 magnitude near the limit of vision. Bright variable stars can therefore be studied effectively without optical aid, provided such a restriction is satisfied. That conclusion has been confirmed by backyard observation of the bright Cepheids _ Cephei, _ Geminorum, and _ Aquilae made during 1998-99 using newly-generated reference charts tied to photoelectric V-magnitudes rather than the usual "visual" magnitudes included on AAVSO charts. The derived light curves for the three bright Cepheids exhibit surprisingly little scatter, and are of potential scientific value for the study of period changes in the variables.