# `Sidereon.Forces.J2`
[🔗](https://github.com/neilberkman/sidereon-ex/blob/main/lib/sidereon/forces/j2.ex#L1)

Earth's oblateness (J2) perturbation force model.

# `acceleration`

```elixir
@spec acceleration({float(), float(), float()}, {float(), float(), float()}) ::
  {float(), float(), float()}
```

Compute the acceleration due to J2 perturbation in ECI.
Ref: Vallado (4th ed), Eq 8-30.

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*Consult [api-reference.md](api-reference.md) for complete listing*