I got hold of what seems to be the abridged Ryom catalogue, (only about 200 pages wheras I expected 721), yesterday. Unfortunately I saw to my horror that this sonata is RV 044 not RV 042.
I think I had better reload it with the right Ryom number and hope the moderators can alter things to stop propagation of errors.
RV 039, originally in E flat, is correct in my posts.
If anyone is interested the six Vivaldi sonatas on IMSLP which are the Paris publication are. (1) RV 047, (2) RV 041, (3) RV 043, (4) RV 045, (5) RV 040, (6) RV 046.
I do not know why the two sequences are different. Perhaps Ryom has manuscript concordance evidence that they were written in his order.