*****************************************************************************
 *It is recommended that it would be appropriate courtesy to acknowledge     *
 *in publications that the flare index data were calculated by the staff of  *
 *Kandilli Observatory. The following statement is suggested:                *
 *"Flare Index Data used in this study were calculated by T.Atac and A.Ozguc *
 * from Bogazici University Kandilli Observatory, Istanbul, Turkey"          *
 *         http://www.koeri.boun.edu.tr/astronomy/findex.html                *
 *****************************************************************************

                              FLARE INDEX

Kleczek (1952) first introduced the quantity "Q = i x t" to quantify the
daily flare activity over 24 hours per day. He assumed that this
relationship gives roughly the total energy emitted by the flares. In
this relation, "i" represents the intensity scale of importance and "t"
the duration (in minutes) of the flare. Some reviews of flare activity
using Kleczek's method are given for each day from 1936 to 2000 by
Kleczek (1952), Knoska and Letfus (unpublished), Knoska and Petrasek
(1984), Atac (1987) and Atac and Ozguc (1998).
The daily flare index of the 21,22,23 Solar Cycles was determined by using the
final grouped solar flares which are compiled by NGDC (National
Geophysical Data Center). It is calculated for each flare using the
formula:
                        Q = (i x t)

where "i" is the importance coefficient of the flare as shown in Table 1, 
and "t" is the duration of the flare in minutes.

                        Table 1
            _________________________________
            Importance   i   Importance   i
            ---------------------------------
            SF,SN,SB    0.5    2B        2.5
            1F,1N       1.0    3N,3F,4F  3.0
            1B          1.5    3B,4N     3.5
            2F,2N       2.0    4B        4.0
            ---------------------------------

To obtain final daily values, the daily sums of the index for the northern 
and southern hemispheres and for the total surface are divided by the total 
time of observation of that day calculated from Solar-Geophysical Data, 
Comprehensive Reports. 

      1986-2000 flare index data are produced by:

 Dr. Tamer Atac                          Dr. Atila Ozguc
Bogazici University                    Bogazici University
Kandilli Observatory and               Kandilli Observatory and
Earthquake Research Institute          Earthquake Research Institute
Cengelkoy-81220 Istanbul               Cengelkoy-81220 Istanbul
Turkey                                 Turkey
e-mail: atac@boun.edu.tr               e-mail: ozguc@boun.edu.tr
fax: 90-216-3321711                    fax: 90-216-3321711
phone: 90-216-3080514                  phone: 90-216-3080514

                            References
Atac, T.: 1987, Astrophys. Space Sci. 135, 201.
Ozguc, A. and Atac, T.: 1989, Solar Phys., 123, 357-365
Ozguc, A. and Atac, T.: 1994, Solar Phys., 150, 339-346, 1994 
Ozguc, A. and Atac, T.: 1996, Solar Phys., 163, 183-191, 1996 
Atac, T.,and Ozguc, A.: 1996, Solar Phys., 166, 201-208, 1996 
Atac, T.,and Ozguc, A.: 1998, Solar Phys., 180, 397-407
Kleczek, J.: 1952, Publ. Inst. Centr. Astron., No. 22, Prague.
Knoska, S and Petrasek, J.: 1984, Contr. Astron. Obs. Skalnate Pleso 12,
165.
                         Acknowledgements
 The authors would like to thank to H.E.Coffey and E.H. Erwin of
WDC-A for Solar-Terrestrial Physics, NOAA E/GC2, Broadway 325, Boulder,
CO, who made available the grouped flare lists.