Extrinsic 1309-1

{
  "heartbeat": {
    "blockNumber": 1307,
    "sessionIndex": 21,
    "validatorsLen": 4,
    "authorityIndex": 1
  },
  "signature": "0xce69db14f5f5e0d5f4677dd91ea6cdc747d4f85c29b63a8b07ab4fb0ac10e45e40abf49c297f539048b92d036809d245c48bc5f39a00d85c21b7d9154ef19e81"
}