Little thread for Sunday, I decided to see if I could figure out exactly when this mass grave in Raqqa appeared on satellite imagery, which may allow it to be linked to a specific incident
First thing, check higher resolution imagery from Digital Globe and Google Earth and Terraserver, which clearly shows the mass grave appeared after Feb 3rd 2017 and before May 24th 2017. Unfortunately there's no images in between those dates. 
At first, images from @planetlabs looks like it might not be too helpful, it's 3m resolution compared to 30-50cm resolution from Digital Globe
But by examining each image sequentially it's possible to see certain feature around the areas the graves were seen in higher resolution imagery seem to vanish between April 10th and April 17th, making it likely the graves were dug between those dates.
The Battle for Raqqa city began in June, so these graves clearly predate that, so the question is what happened in the area in April that resulted in all those mass graves being dug?
