are we taking the weyland files as canon

iv not seen the blue ray discs of Prometheus but I believe there is quite a bit of extra information provided in these files. my question is mostly centered around weyland acknowledging that they are aware of the signal coming from lv426, though I don't believe he doesn't go into the specifics of the signal so this signal may be different to the warning found in alien, but if it is the warning message and if ridley was the one who wanted this bit of info put the, then is it safe to say the derelict has been there for a very long time?