Shapes of RR Lyrae light curves can be described in terms of Fourier coefficients which past research has linked with physical characteristics such as luminosity , mass and temperature .
Fourier coefficents have been derived for the V and R light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC .
In general , the Fourier phase differences \phi _ { 21 } , \phi _ { 31 } and \phi _ { 41 } increase and the amplitude ratio R _ { 21 } 
decreases with increasing period .
The coefficients for both the V and R magnitudes follow these patterns , but the phase differences for the R curves are on average slightly greater , and their amplitudes are about 20 % smaller , than the ones for the V curves .
The \phi _ { 31 } and R _ { 21 } coefficients have been compared with those of the first overtone RR Lyrae variables in the Galactic globular clusters NGC 6441 , M107 , M5 , M3 , M2 , \omega Centauri and M68 .
The results indicate that many of the LMC variables have properties similar to the ones in M2 , M3 , M5 and the Oosterhoff type I variables in \omega Cen , but they are different from the Oosterhoff type II variables in \omega Cen .
Equations derived from hydrodynamic pulsation models have been used to calculate the luminosity and temperature for the 330 bona fide first-overtone variables .
The results indicate that they have \log L in the range 1.6 to 1.8 { L _ { \odot } } and \log T _ { eff } 
between 3.85 and 3.87 .
Based on these temperatures , a mean color excess E ( V - R ) = 0.08 mag , equivalent to E ( B - V ) = 0.14 mag , has been estimated for these 330 stars .
The 80 M5-like variables ( selected according to their location in the \phi _ { 31 } - \log P plot ) are used to determine a LMC distance .
After correcting for the effects of extinction and crowding , a mean apparent magnitude < V _ { 0 } > = 18.99 \pm 0.02 ( statistical ) \pm 0.16 ( systematic ) has been estimated for these 80 stars .
Combining this with a mean absolute magnitude M _ { V } = 0.56 \pm 0.06 for M5-like stars derived from Baade-Wesselink analyses , main sequence fitting , Fourier parameters and the trigonometric parallax of RR Lyrae , we derive an LMC distance modulus \mu = 18.43 \pm 0.06 ( statistical ) \pm 0.16 ( systematic ) mag .
The large systematic error arises from the difficulties of correcting for interstellar extinction and for crowding .