The book that I am working on has an index of authors. On some pages of the book an author's name only occurs in a footnote.

Is it possible in ConTeXt to mark, in the index, those occurrences in footnotes so that in these cases not only the page number appears in the index but also, preferably as superscript, the footnote number on that page?

As for example

Arnold, Franck Th.  9, 283    indicating footnote 3 on page 28 (Sorry, I cannot make a superscript in this mail editor)

What I certainly don't want is separate index entries for those authors. Each author name should occur in the index only once.