hi! fyi, you'll find some general information about the archives in these earlier posts

• How many historical documents is the Vatican library sitting on? Any denied research requests?

• Why does the Vatican restrict access to so much of its archives?

• What do we know about the contents of the Vatican libraries?

• What cool/important items are in the Vatican Library and secret archives?

I don't know how far the archives are opened

There is a standard 75 year wait to open the archives for a given pontiff. With Pius XII being elected in 1939, adding 75 years to that gives us 2014. Said archives are not yet available, and there has been no comment as to why (though this is not unusual). Francis has said that they will be made available "soon," but that word takes on a different meaning when you're talking about the Vatican. So we're basically caught up to 1939, and we're waiting for the documents from 1939 to 1958.

Maybe someone will tell me if this document has been published now but I always wondered what exactly was the secret letter sent by the Emperor Franz Josef of Austria-Hungary to the Pope concerning the death of Archduke Rudolph.

This letter should contain what the imperial family knew of the so-called " suicide " of Rudolph. Indeed if the Emperor needed to send a secret/coded letter to the Pope in order to ask for Catholic funeral it was certainly because Rudolph never commited suicide but was murdered. ( after all, in the 80s, former Empress Zita mentioned that Rudolph had been murdered and that all the imperial family knew that in some way France and Clémenceau may have been involved ).

This letter, if it still exists may contain what Franz Josef knew of his son's death, enough to convince the Pope that the Archduke never killed himself and deserved Catholic funerals despite what the public and official reason was.