What's the best coordinate system for UK in ArcGIS Pro and Online?

[SophieHorsley]

I use ArcGIS Pro to create maps and then share them with my organisation in ArcGIS Online. I use a lot of data from Environment Agency, Natural England etc. overlaid on either a Google aerial photo or OS Street Map. What's the best coordinate system to use? If I use British National Grid in ArcGIS Pro and then load the map into Online lots of the datasets are slightly offset.

[Anonymous User]

Hi Sophie,

That is a great question.

I work in New Zealand and also have to work with multiple coordinate systems. Different organisations will provide their data in local projections which can make publishing and using layers and services within one single web map quite tricky.
I usually try to bring everything back to one single proejction. The default projection for ArcGIS Online is WGS 1984 Web Mercator (Auxiliary Sphere).

You may want to take a look at this article by Esri UK: ArcGIS Online brings projections to our world — Esri UK 

I will usually use a local projection within ArcGIS Pro when it comes to analysis (calculating distances, areas,...). But when publishing my results to ArcGIS Online, I will keep everything to Web Mercator.

I don't know if this is of any help...?

Alix