# Historical API end\_timestamp incorrect **URL:** \ **Category:** API\ **Created:** [December 21, 2024, 11:38pm UTC](https://community.purpleair.com/t/historical-api-end-timestamp-incorrect/10989 "2024-12-21T23:38:00Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![dwhitemv](https://sea2.discourse-cdn.com/flex020/user_avatar/community.purpleair.com/dwhitemv/32/1508_2.png) [@dwhitemv](https://community.purpleair.com/u/dwhitemv)\ **Post date:** [December 23, 2024, 8:30pm UTC](https://community.purpleair.com/t/historical-api-end-timestamp-incorrect/10989/3 "2024-12-23T20:30:44Z")
`start_timestamp` and `end_timestamp` are NOT related to the period of record for the sensor. They represent bounds of the submitted query, nothing more. As per the [API docs for the get-sensor-history call](https://api.purpleair.com/#api-sensors-get-sensor-history) and [this post](https://community.purpleair.com/t/loop-api-calls-for-historical-data/4623), the valid values for `end_timestamp` depend on the requested average time and the maximum amount of data returned per call. The returned `end_timestamp` was the one used in the call. For a 1 hour average you can request up to 180 days of data. The data are returned unordered. `end_timestamp` defaults to `start_timestamp` + the maximum time limit for `average`. Best not to rely on defaults and provide a `start_timestamp` and `end_timestamp` in your call so you get the data you are expecting. Along that line, there does not appear to be an API query that provides the period of record for a given sensor. `date_created` should be a safe lower bound – no data could possibly exist before then – but if a sensor has gone offline there is no way to know when the last observation was without fetching the entire history up until current. There doesn’t seem to be a field for indicating when a sensor was archived, if that happened, either. --- _[View the full topic](https://community.purpleair.com/t/historical-api-end-timestamp-incorrect/10989)._