The use of ô versus ō in rōmaji


Perhaps this question is completely unimportant, but I do not know if it is.

There is a very influential mathematical paper by Alexander Grothendieck often
called his Tôhoku paper, because of the journal that published it in 1957.

When I look online now, the only people who use the accent ô are
mathematicians referring to this paper. Everybody who is just writing about
the place 東北地方 uses the accent ō and writes Tōhoku.

Wikipedia suggests the spelling Tôhoku is the Kunrei-shiki or Nihon-shiki
version, while Tōhoku is the Hepburn or Revised Hepburn version. Is that true?

Do Japanese speakers today make any distinction between ô and ō in
romanization? Or is it just a trivial choice between notations?




As @naruto notes, the difference between _Tôhoku_ and _Tōhoku_ is only a
difference of romanization systems. (Both are correct transliterations of 東北
in their respective systems.) A number of romanization systems are used in
Japan, so Japanese speakers will probably not give it a second thought.

Presumably the reason that the paper is referred to as the _Tôhoku_ paper is
that at the time of publication (1957) the official name of the journal was
_Tôhoku Mathematical Journal_. Only in 1999 was [the name of the journal
changed to _Tohoku Mathematical
Journal_](https://www.math.tohoku.ac.jp/tmj/Eabout.html) (unfortunately
obscuring the long vowel by not using any standard romanization):

> First, we redesigned the cover from Volume 51 in 1999, and adopted "Tohoku
> Mathematical Journal" instead of "Tôhoku Mathematical Journal" as the
> offical name.

The journal appears to have a Japanese name 東北数學雑誌 _Tōhoku Sūgaku Zasshi_ (in
Hepburn) on the cover.

[![tohoku](https://i.stack.imgur.com/Se3z6.png)](https://i.stack.imgur.com/Se3z6.png)

But if the official name was _Tôhoku Mathematical Journal_ (now _Tohoku
Mathematical Journal_ ), then this is the name one should probably use to
refer to it.

