COMPILING the years of STEREO.
.W.I.P.
Location, Location.
In the picture above, this tells us the area of the night sky they believe it to be around. Lets take a look at it.
This is the general area of the sky, that's the center of the milky way.
Almost in the same area but a little farther out. This unmarked mass, however is not The Seven sisters, and appears to show up on sky maps.
Here is a picture of the Pleiades below.
Similar, but not quite, there fore I think it is safe to say, the mass on STEREO is not the Pleiades.