Improved interplanetary magnetic field propagation timing by correction of the phase front orientation using two spacecraft

We present a method of calculating the interplanetary magnetic field propagation delay in the solar wind that that uses observations from two spacecraft to partially correct the phase front orientation. A third spacecraft is used to test the accuracy of the method. We show that the two-spacecraft method reduces the overall propagation error by 23%. The reduction in the error is greater for larger values of the perpendicular spacecraft separation; for perpendicular separation less than 13(RE), the error reduction is only 7%, while for perpendicular separation greater than 13(RE), the error reduction is 26%. In addition, the two-spacecraft technique allows the calculation of the uncertainty in the propagation delay in individual cases, which allows the user to identify cases in which the propagation is more precise than on average.