We have presented new spectroscopy of the open cluster Blanco 1, primarily examining the G and K dwarf population which make up the vast majority of published photometric observations. We have revised cluster membership based on available photometry and spectroscopy, and have included accurate positions for all these stars. We recognise that our memership list is still contaminated by field stars. Cluster membership will be improved when the proper motion survey of Platais et al. (1996) is published.
By quantifying the number of H
emitters within the
cluster's K dwarf population we obtain a new age estimate for
the cluster of 90 
25 Myr. This is substantially greater
than previous estimates based on isochrone fitting to the
main-sequence turn-off. We believe this dichotomy may be
explained by a paucity of high-mass stars and doubt as to the
position of the bluest star on the CM diagram. This new age
measuring technique is found to be more sensitive than lithium,
and its use is recommended for young clusters, where a strong
correlation exists between activity-rotation and age.
Acknowledgements
We would like to thank Charles Prosser
for making available all his compiled data on 
Persei,
the Pleiades and Hyades clusters. Many thanks also to Imants
Platais who very kindly supplied us with preliminary information
from his recent proper motion survey which is expected to be
published shortly. We thank Mike Irwin for his help with the
APM, also Martin Hendry, Andrew Cameron and John Stauffer for
useful comments on the statistics and interpretation of our
data. Finally we wish to thank the staff at the AAT,
particularly Raylee Stathakis, for help during the observations.