is Visvamitrasana :)
Off the top of my head I thought it was (insert Sanskrit term) Vasisthasana (that’s side-plank) in the way that you put “Parivrtta” before every asana that’s “revolved,” like Parivrtta Ardha Chandrasana (revolved half moon) or “Utthita” before “extended” poses like Utthita Parsvakonasana (extended side angle). Anyway, no such luck- it’s a completely different term that I would never have known off the top of my head because I don’t practice it and have never taught it myself.
Er, sorry for the Sanskrit babbling. I love Sanskrit, in case anyone on tumblr doesn’t know that already :P
And I’ve always seen it taught from a lower point of entry, instead of from Trikonasana like I’ve seen you two doing. It might be worth a try to enter it in the way that Kathryn writes about in her Challenge Pose blog on Yoga Journal. She did a post about Visvamitrasana a couple months ago and I remembered it. Here it is!