I have a bunch too ^_^ (though not by this 
circle). Sometimes doujinshi are by famous 
artists, so if you do some research into who the 
circle members are you may find that although 
this person may not have been involved with the 
Gundam project, they may be a popular artist of 
some other "real" series.

For example, famous (adult) doujinshi author 
Shinji Yamaguchi is also the author of the Maho 
Tsutai Tai (SP??) manga series (under her real 
name, Yamaguchi is her pen name).

Mine aren't by famous artists but I love each and 
every sketch ^_^

enjoy your find, it's a beauty!
misa