\def\rmpt@#1.#2{#1#2}
\def\put@pt#1#2.#3{\ifx#3\empty#2#1\else #2.\kern-.25em\relax#1\rmpt@#3\fi}
% magnitude
\def\m#1{\ensuremath{\put@pt{^m}#1.\empty}}
% degrees
\def\arcdeg#1{\ensuremath{\put@pt{^\circ}#1.\empty}}
% arc minutes
\def\arcmin#1{\ensuremath{\put@pt{'}#1.\empty}}
% arc seconds
\def\arcsec#1{\ensuremath{\put@pt{''}#1.\empty}}
\def\Ang{\mbox{\,\AA}}