аж = ажээ = байжээ Нээлтээ дахин батлахаар 1920 онд одон орон судлаач их гоё хувцастай ирсэн байжээ. This sentence is neutral. It simply says that astronomers wore very nice clothes to their opening ceremony. Нээлтээ дахин батлахаар 1920 онд одон орон судлаач их гоё хувцастай ирсэн аж. "Аж" adds somewhat sarcastic meaning to the sentence. It's hard to say without knowing the context, but one might guess that the writer thought it was silly to dress up, or he finds the opening ceremony itself quite stupid. The