It's not that they did the background subtraction in a non-standard way, it's that they didn't have a measurement of the background to subtract (it being too ha

It's not that they did the background subtraction in a non-standard way, it's that they didn't have a measurement of the background to subtract (it being too hard to measure directly), so they instead estimated what the background would look like and subtracted that. Some of their peers are claiming their estimate is bad, but the researchers are sticking by it.