[phenixbb] green ball in aspartate

Hi Everybody. Does anybody knows what could this be? Blue map at 1rmsd Green and red map at 3.5 rmsd Purple map (FEM map) at 1rmsd Conditions 100mM sodium acetate, NaCl 10% w/v, cryo=glycerol 30 % v/v; protein is hen egg white lysozyme (usual condition, usual protein and ohh..almost forget it.. ascorbic acid at 0.5 M) A water molecule overlaps with the oxygen atom (OD1) of the aspartate residue. So it is not a water molecule. Any ideas? (In coot -> validate-> difference map peaks and holes-> its the only one at 7.7 rmsd) Thanks