Transit

The Transit namespace searches for the next or previous transit events of one graha from a LocatedMoment. It is mechanics-only: each event reports the exact moment, longitude, kind, and retrograde state. There is no interpretation here.

import { Effect } from "effect";

import { AstroParams, Transit, Swisseph } from "astro-ascendant";

const ingresses = await Effect.runPromise(
  Transit.findTransits({
    planet: "Jupiter",
    from: locatedMoment,
    count: 3,
    direction: "forward",
    kinds: ["sign-ingress"],
    maxYears: 12,
  }).pipe(
    Effect.provide(AstroParams.layer({ ayanamsa: "Lahiri", houseSystem: "WholeSign" })),
    Effect.provide(Swisseph.SwissephLayer),
  ),
);

Public exports

export * from "./error.js";
export * from "./model.js";
export { findTransits } from "./find.js";

findTransits(request) is the single entry point. It requires the AstroParams and Ephemeris Effect layers. The low-level sampling helpers (searchRawHits, sampleAt, normalize360, and related types) are also re-exported for custom search tooling.

Event kinds

Cusp targets are the natal house cusps at from under the shared AstroParams. Charts attach afterwards only when includeCharts asks.

Request fields

Result and guarantees

Each TransitEvent contains planet, moment, longitude, kind, is_retrograde, direction, provenance, an optional D1 sign, and an optional calculation when includeCharts requested divisions.

• Every zero-crossing counts in strict time order, so retrograde triples yield three events.
• Refinement bisects to precisionMinutes (default 1).
• An exhausted maxYears window fails with typed TransitSearchExhausted (carrying the partial found events and searchedUntil) instead of a short list.
• Invalid requests fail with typed TransitValidationError.