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You could try implementing one callback for all three messages using message_filters. You can either use an exact time policy if all topics are exactly in sync or an approximate time policy to allow small differences between their timestamps. An example and a more detailed description is given here:

http://wiki.ros.org/message_filters#Policy-Based_Synchronizer_.5BROS_1.1.2B-.5D

In the callback you could finally write the information you need from your three messages into one txt file.

Best

Tim