<!-- source: https://secondlayer.tools/docs/api-reference#get-burn-block-proof -->

## Burn block behind a consensus hash

`GET /v1/proofs/burn/{consensus_hash}`

The sortition preimage that hashes to a block header's `consensus_hash` (RIPEMD160(SHA256(preimage))). Bytes 4..36 of the preimage are the Bitcoin block hash, which pins the header's burn height against Bitcoin proof of work. Free and keyless: never metered, no account needed. Hosted limits: 10 requests per second per IP (1 for witnesses), or 20 (2) per account with a key. Bytes are passed through unchanged; verify them, do not trust them.

### Path parameters

| Name | Type | Description |
| --- | --- | --- |
| `consensus_hash` | string, required | The header's `consensus_hash`: 40 hex characters, `0x` optional. |

### Returns

One `ProofBurnBlock` object.

### Responses

- `200` The preimage and the burn block it names
- `400` A path or query parameter is malformed (`VALIDATION_ERROR`): hashes must be exact-length hex, heights non-negative integers
- `401` This bind requires the instance token, and it was missing or wrong
- `404` No sortition with that consensus hash
- `429` Rate limited; retry after `Retry-After` seconds
- `502` The node or proof sidecar could not be reached, or answered with an unexpected status (`PROOF_SOURCE_ERROR`)
- `503` `PROOFS_UNAVAILABLE`: this instance has no proof sidecar (`PROOF_SIDECAR_URL` unset). `PROOF_SOURCE_BUSY`: the sidecar is busy; retry after `Retry-After` seconds

### Example

```bash
curl https://api.secondlayer.tools/v1/proofs/burn/e55512fc4a1fd7b3c6b0bcd1b0b2d28a7e3f9c11 \
  -H "Authorization: Bearer $SECONDLAYER_API_KEY"
```

```json
{
  "consensus_hash": "e55512fc4a1fd7b3c6b0bcd1b0b2d28a7e3f9c11",
  "burn_height": 970269,
  "bitcoin_block_hash": "00000000000000000001b6b3c5a9e2b5d8f8f1c0a7e4d3b2a1908f7e6d5c4b3a",
  "preimage": "0100000000000000000000000001b6b3c5a9e2b5d8f8f1c0a7e4d3b2a1908f7e6d5c4b3a…"
}
```