I replied to Simon off-list initially; as a first posting, his was
moderated (*), but for some reason, it didn't pop up after I approved
it until quite a bit later, and I thought Yahoo! had chewed up his post.
Anyway, I replied as follows :

Your observations are okay, except for two things.

First, the ':' between HH:MM:SS and dd:mm:ss shouldn't be there. Use
spaces instead.

Second, this observation :

G4121 2016 11 01.86856 05 19 00.78 +85 38 14.3 V Z49

is quite wrong in RA. Find_Orb doesn't handle that particularly well;
at present, it's not bright enough to realize it ought to just exclude
that observation and press on with a solution using the other observations.
(As it happens, I got an idea a couple of days ago for spotting such
isolated outliers... doesn't help you right now, though!)

-- Bill

(*) Note to new members: you're moderated until I see your first post.
I started doing that a few years ago, after porn spammers took advantage
of the list being completely unmoderated to discuss "heavenly bodies" of
a very different sort.