Extrinsic 1574-1

{
  "heartbeat": {
    "blockNumber": 1573,
    "sessionIndex": 26,
    "validatorsLen": 1,
    "authorityIndex": 0
  },
  "signature": "0x762471028dc0ead77fe8fe852b0a5826b8c5e41d1f787d9a812193d074bdd1099c8a4591fd0ab46ef1dd41a61b0cb479464caed492e1c67f2886f839644f7a88"
}