is a FORTRAN code for disentangling (i.e. a separation of component spectra and simultaneous solution of system parameters) of spectroscopically variable stellar systems using Fourier transform in the wavelength domain. KOREL was developed together with the method itself by P. Hadrava on the basis of experience with his code FOTEL (for FOTometric ELements) and inspiration by the Cross-correlation method (that is why KOR(elation)EL(ements)). The method was later denoted as disentangling to point out the importance of simultaneous spectra decomposition and parameters fitting well justified by Simon and Sturm (1994, A&A 281, 286) for their independently developed method based on SVD in direct wavelength domain.
An alternative code fd3 for Fourier disentangling was developed by Sasa Ilijic.

The code itself is now available as a Virtual Observatory Service on VO-KOREL web-page of Astronomical Institute of the Czech Academy of Sciences.

A description of KOREL and related methods can be found in the document KOREL - User's guide in Publications of the Astronomical Institute No. 92, pp. 15-36 (2004). An enlarged version was prepared by the author for the First Summer School of Disentangling. Its updated version is available in astro-ph document "Disentangling of spectra -- theory and practice". The disentangling was also taught by the author at several dedicated courses at Charles University and COMU or a miniworkshop at ESO.

Some of the sample data for testing the run of KOREL, which are described as exercises in the Summer-school lecturenotes, can be downloaded here:
Ex1 - KOR0801A.DAT, KOR0801A.PAR, KOR0801B.DAT, KOR0801B.PAR.
Ex2 - korel2a.dat, korel2a.par, korel2b.dat, korel2b.par, korel2c.dat, korel2c.par.
Ex3 - korel3a.dat, korel3a.par, prekor3.lst, prekor3.par, 55U03870.ASC, 55U03886.ASC, 55U03935.ASC, 55U03942.ASC, 55U03954.ASC, 55U04039.ASC, 55U04059.ASC, 55U04102.ASC, 55U04149.ASC, 55U04300.ASC, 55U04562.ASC, 55U04587.ASC, 55U04698.ASC, 55U04722.ASC, 55U07435.ASC, 55U07454.ASC, 55U07579.ASC, 55U07593.ASC, 55U07624.ASC.
Exfd3 - korelfd3.dat, korelfd3.par

A recent version of PREKOR-code can be downloaded here. Note, please, that it is executable under DOS.

Theory of Fourier disentangling is described in a series of papers (1995:) A&AS 114, 393, (1997:) A&AS 122, 581, (2001:) Astrotomography, (Eds. H.M.J. Boffin et al.), Springer 2001, p. 261, (2003:) ASCP 288, 149, (2004:) ASCP 318, 86, (2005:) Astrophys. Sp. Sc. 296, 239, (2006:) A&A 448, 1149, Ap&SS 304, 337, IAUS 240, 121, (2009:) A&A 494, 399, A&A 507, 397.

Some examples of its use can be found in papers (1996:) A&A 315L, 401, (1997:) A&A 319, 867, A&A 322, 565, Contr.Skal.Pl. 27, 41, (1998:) A&A 332, 909, (1999:) A&A 345, 531, A&A 345, 855, (2000:) A&A 353, 1009, IAUS, 200, p.109, A&A 358, 553, (2002:) ApJ 564, 260, ApJ 574, 771, (2003:) ApJ 587, 685, A&A 405, 1087, A&A 408, 611 etc.

Petr Hadrava,
Astronomical Institute of the Academy of Sciences of the Czech Republic,
Bocni II 1401
CZ 141 31 Praha 4,
Czech Republic
e-mail: had(at)sunstel.asu.cas.cz
tlf.: +420 226 258 421;
Revised 29. 7. 2014