This book may help you:
Osprey - Aviation Elite Units Series 025 - Jagdgeschwader 53 Pik As
It has a profile of Harder's Bf 109 F, the makings indicate he was a pilot of the Staff of III Gruppe of JG 53 and does not have the 'O' crossed
Your image is that of Harder's Bf 109 E.
I hope this is useful