> For the complete documentation index, see [llms.txt](https://k4k3ru.gitbook.io/k4k3ru-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://k4k3ru.gitbook.io/k4k3ru-docs/api/market-hub/order-book-subscribe.md).

# Subscribe to Consolidated OrderBook Data

`MarketHub.OrderBook.Subscribe` creates an authenticated WebSocket subscription for venue-independent market-depth updates. Use `MarketHub.OrderBook.Unsubscribe` with the same normalized parameters to remove it.

## Subscribe

```json
{
  "id": "1",
  "method": "MarketHub.OrderBook.Subscribe",
  "params": {
    "marketType": "spot",
    "symbol": "BTC/USDC",
    "depth": 3
  },
  "auth": {
    "apiKey": "YOUR_API_KEY",
    "timestamp": 1788533857,
    "nonce": "UNIQUE_NONCE",
    "signature": "REQUEST_SIGNATURE"
  }
}
```

The acknowledgement returns the normalized subscription parameters. `depth` defaults to `3` and accepts values from `1` through `20`.

Subsequent `ob` events contain the compact OrderBook result fields documented by [Get a Consolidated OrderBook Snapshot](/k4k3ru-docs/api/market-hub/get-order-book-snapshot.md):

```json
{
  "e": "ob",
  "data": {
    "ac": "crypto",
    "mt": "spot",
    "s": "BTC/USDC",
    "d": 3,
    "b": [{"p": "78891.9", "q": "0.016801"}],
    "a": [{"p": "78892", "q": "0.01838"}],
    "svc": 2,
    "v": 6842374982615800523,
    "ts": 1788533857086000
  }
}
```

Order-book and eligible synthetic BBO updates can both produce a new consolidated depth event.

## Unsubscribe

```json
{
  "id": "2",
  "method": "MarketHub.OrderBook.Unsubscribe",
  "params": {
    "marketType": "spot",
    "symbol": "BTC/USDC",
    "depth": 3
  },
  "auth": {
    "apiKey": "YOUR_API_KEY",
    "timestamp": 1788533860,
    "nonce": "ANOTHER_UNIQUE_NONCE",
    "signature": "REQUEST_SIGNATURE"
  }
}
```

Subscribe and Unsubscribe require valid signed WebSocket requests. Unsubscribe parameters must identify the same normalized subscription, including `depth` and any `sourceFilter`. Individual contributing Venue names are not returned.

The same bid-anchored non-crossed consolidation as Get applies: asks at or below the best bid are excluded before the requested depth is selected.


---

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