I’m using yt to generate halo catalog. However, when I check the halos created by HaloCatalog function, I found the corresponding comoving unit uses the expansion factor of the universe rather than a_box. 

For example, My boxsize is 20cMpc/h, but if I use .in_units(‘Mpccm/h’), the halos are offset by some amount (see attached). I wonder if this is a bug in converting physical unit to comoving unit?

Thanks,

Huanqing