 Outgoing null oblate spheroidal coordinates

ID: outgoing-null-oblate-spheroidal-coordinates

u = t - r

R = r

, and choose an azimuth

φ

satisfying

d φ = d ϕ - \frac{a}{R ^{2} + a ^{2}} d R .

Then

d s^{2} = - d u^{2} - 2 d u d R + 2 a sin^{2} θ d R d φ + (R^{2} + a^{2} cos^{2} θ) d θ^{2} + (R^{2} + a^{2}) sin^{2} θ d φ^{2},

\partial_{R}

is null.

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