# Biorhythm Best Days

`POST https://api.astroway.info/v1/wellness/biorhythm/best-days`

The highest-scoring days in a range (up to 366 days): score = 100 x (sum of the three cycle values + 3) / 6, critical days left out by default. A historical model, not a prediction and not health advice; the disclaimer travels with the answer.

Group: Wellness. Auth: `X-Api-Key` header. Operation ID: `wellness_biorhythm_best-days`.

## Parameters

| Name | In | Required | Type | Description |
|---|---|---|---|---|
| `fields` | query | no | string | Comma-separated dotted paths, relative to `data`, to keep in the response. A path is applied to every element of an array, so `planets.name` means the name of each planet. Paths that match nothing come back in `_fields_unmatched`; a list where nothing matches at all is a 400, because an empty object would be a confident wrong answer. |
| `precision` | query | no | integer | Round every non-integer number in the response to this many decimal places. Integers are left alone, because an id is not a measurement. Ecliptic longitudes ship with fourteen decimals by default; 2 is about a tenth of an arcminute. |
| `Idempotency-Key` | header | no | string | Unique per logical operation, kept across retries. For 24 hours from the first request, a repeat with the same key, method, path, body and query string returns the stored response with `Idempotent-Replayed: true` and costs 0 credits. The same key with a different body or query string is a 409 `IDEMPOTENCY_KEY_REUSED`; a repeat while the first is still running is a 409 `IDEMPOTENCY_IN_PROGRESS`. Only 2xx responses are kept. See /idempotency/. |

## Request body

| Field | Type | Required | Description |
|---|---|---|---|
| `birthDate` | string | yes |  |
| `rangeStart` | string | no |  |
| `rangeEnd` | string | no |  |
| `count` | integer | no | How many days to return, best first. |
| `excludeCritical` | boolean | no | Leave out days on which any cycle crosses zero. |

```json
{
  "birthDate": "1990-06-15",
  "rangeStart": "2026-12-01",
  "rangeEnd": "2026-12-31",
  "count": 3
}
```

## Responses

| Status | Meaning |
|---|---|
| 200 | Successful calculation |
| 400 | Validation error |
| 401 | Missing or invalid API key |

### Success fields, under `data`

| Field | Type | Required | Description |
|---|---|---|---|
| `birthDate` | string | no |  |
| `range` | object | no |  |
| `range.start` | string | no |  |
| `range.end` | string | no |  |
| `range.days` | number | no |  |
| `bestDays` | object[] | no |  |
| `formula` | string | no |  |
| `disclaimer` | string | no |  |

## Example

```bash
curl -X POST https://api.astroway.info/v1/wellness/biorhythm/best-days \
  -H "X-Api-Key: aw_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "birthDate": "1990-06-15", "rangeStart": "2026-12-01", "rangeEnd": "2026-12-31", "count": 3 }'
```

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Rendered from https://api.astroway.info/v1/openapi.json. HTML page: https://api.astroway.info/docs/api/operations/wellness_biorhythm_best-days/