I'm researching the early Bábí communities and am finding the usual secondary sources thin on contemporary non-Bábí accounts of the events of 1848 — particularly the Conference of Badasht and its immediate aftermath. The Táríkh-i-Jadíd (New History) and the Nabil Narrative are invaluable, of course, but both have the obvious limitation of being internal Bahá'í sources written decades after the events. I'm looking for contemporary Persian, Ottoman, or European diplomatic sources that might corroborate or complicate the picture.
I know Moojan Momen did some work with British diplomatic archives in the 1980s and Denis MacEoin has written on the Bábí period extensively, but I'm not sure how systematically the Iranian state archives (now held in Tehran) have been mined for this period. Has anyone worked with those directly, or know of scholars who have?