It is an object to provide a vacuum apparatus capable of evaluating its cleanness precisely by surely monitoring particles including deposits readily detached from the apparatus, and a particle monitoring method and program employed therein, and a window member for particle monitoring. In the other cases, the navigation device changes the position determination accuracy of the receiver to a low accuracy. Communication channel information is designated as modified communication channel information. The dust groove includes first and second faces spaced along the axis and a third face extending between the first and second faces. In some cases, this handle may be directly that of the target frame itself, in which case the particular frame communicates the message directly with the target frame.