Have you ever had questions about how time works in ArcGIS Online?
This two minute crash course might provide some insight.
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For more information on working with date and time in ArcGIS Online:
Kelly Gerrow-Wilcox's excellent blog post on mastering "space and time" in ArcGIS Online
ArcGIS Online documentation on working with date and time
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My history of Time Zones, UTC and Unix Time are far from complete. The following resources will provide additional context:
NPR Planet Money story on Standard Time in the US
More on Sir Sandford Fleming
Unix Time Converter
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Thanks for watching! Leave me any comments or questions below and I will make sure to respond.