Thanks to a post from the mapbox colleagues I’ve found out that new Landsat 8 scenes are already available on EarthExplorer. The data is great!!!
But first you need to create an account which is straight forward and easy also for non-US citizens. The registration process is done in less than 2 minutes but it seems that e-mail verification by the USGS takes some more time. Nevertheless you will have access to the data without this as well.
First: type your desired location and maybe dates in the first searchbox at EarthExplorer:
Press on Data Sets to select desired data. You can find Landsat 8 data under the Landsat Archive folder:

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p align=”justify”>Just click on results in the last step and zou will get a preview of available granules wich can be overlaid in the current googlemaps scenery. I was very surprised to be able to download data from June 2013 for my favourite lake Ugii Nuur in central Mongolia, which is nearly real-time when it comes to remote sensing data…:

So, happy downloading guys!
