Intrinsic colour calibration for F, G, K stars
  We derive an intrinsic colour calibration for F--K stars using broad band Johnson colours and line indices KP and HP2. Through this calibration we can determine E(B-V) of an individual star within 0.03 mag. The E(B-V) values thus derived are in excellent agreement with those derived from Stromgren photometry through the Schuster & Nissen (1989) calibration. The agreement is also good with the reddening maps of Burstein & Heiles (1982) and Schlegel et al (1998), although in this case there exists a small offset of about 0.01 mag. This calibration may be applied to the large body of data of the HK survey extension which will be published in the near future. 
Piercarlo Bonifacio (1), Elisabetta Caffau (2), Paolo Molaro (1)((1)   Osservatorio Astronomico di Trieste,(2) Istituto Magi...