Visual Observations of delta Cephei: Time to Update the Finder Chart (Abstract)!

Volume 39 number 1 (2011)

David G. Turner

Saint Mary University, Department of Astronomy and Physics, Halifax, Nova Scotia, B3H 3C3, Canada; turner@ap.smu.ca

Abstract

(Abstract only) The current AAVSO finding chart for d Cephei continues to reflect the notion that visual eye estimates need to refer to reference stars for which the cited visual magnitudes on the Johnson V system have been adjusted for a color correction to the eye V-system reflecting what is typical of the “average”AAVSO observer. The correction for the best AAVSO observers, however, appears to be negligible, given that the collected phased eye estimates of d Cep over the past decade (or more) follow a light curve that is greatly suppressed in amplitude from that displayed for Johnson V-band data. The author has previously (1999) advocated the use of a modified finder chart for d Cep that doubles the number of suitable reference stars and eliminates the problem of a suppressed light amplitude in the light curve. As shown here, light curves generated with such a finder chart are also more suitable for studies of period changes in Cepheids like d Cep using O–C analyses.