The bolder letters may not be Aurora Grotesk Bold, but they certainly appear to be based on it—or, at least, the 1928 C. E. Weber release of same.

This sign was most likely silk-screened, so whoever cut or burned the stencil for the sign may have made a few amendments to an existing design—most notably, rounding the D a bit.

thanks. do you have a scan of that 1928 release? the scans i've seen (and dada grotesk, which is based on it) have quite the different lowercase 'a', although there's a definitive relation between aurora and this.

the specimen of the Weber release in Encyclopædia of Type Faces—which reads Das Bauhaus De—shows a slightly flatter top on the /a/, and a more pronounced trap at the bottom where the bowl meets the stem. But—again—if the stencil was hand-cut, the artist may have taken a few other liberties besides making the /D/ less boxy.

you're right, there are quite a few irregularities in there. i guess it was a sloppy hand-cut of aurora then, most likely. thanks!