Quoted from: https://ccmc.gsfc.nasa.gov/modelweb/ionos/auroral_oval.html
Parameter: Mathematical representation of the auroral oval
Brief Description:
Holzworth and Meng (1975) provide a parameterization of the Feldstein (1963) auroral ovals. Feldstein specified seven different ovals for seven levels of magnetic activity. The model describes the Corrected Geomagnetic Latitude (CGL) of the equatorward and polward boundaries of the oval in terms of Magnetic Local Time (MLT). Holzworth and Meng use a seven parameter Fourier series. Their 1975 publication includes the coefficients for the seven Feldstein ovals. A fortran program computes the CGLs for given MLT and level of magnetic activity (0-6). Please note that coordinate conversions from geographic to corrected geomagnetic (CGM) coordinates and vice versa can be done online at CGM page.
Availability: FORTRAN program can be retrieved fromCCMC's anonymous FTP site.
References:
Y. I. Feldstein, On Morphology and Auroral and Magnetic Disturbances at High Latitudes, Geomagn. Aeron. 3, 138, 1963.
R. H. Holzworth, C.-I. Meng, Mathematical Representation of the Auroral Oval, Geophys. Res. Lett. 2, 377, 1975.