An observer can be taken to be that which makes a representation from the received information, so the same for both scales. However at the quantum scale there is interaction with what is observed - At the quantum scale there is provocation or a trial of some kind whereby the system is made to respond and that response is what is detected and made into the representation. There is no interaction with astronomical objects when they are observed via the processing of received em information. At that large scale the state of motion affects what em information is received to be formed into the representation that is produced. It is a one way relationship of information receipt leading to the product.
What would agreement of observation at the different scales entail, how does that word apply?