Is tachanun said at a bar mitzvah boy's aliyah latorah that takes place on a day when tachanun is normally said (basically Monday and Thursday)?
I've been to a few of these, and seen different cases. Once, tachanun was skipped because of a brit that day. Another time tachanun was said, but then someone said afterwards that maybe it shouldn't have been.
I think it might depend on when the actual birthday (bo bayom) is. (I've heard as much.)
So, what's the law, and what is the source/reasoning behind it?