Arthur Matthew Weld Downing FRAS (13 April 1850 – 8 December 1917) was an Irish mathematician and astronomer.

He then went on to study in Trinity College Dublin, from 1866, receiving a scholarship in science graduating with a BA in 1871 with a gold medal in mathematics.

In one paper, he worked with George Johnstone Stoney on the perturbations of the Leonid meteors, predicting and explaining the sparseness of the 1899 shower.

He collaborated with his American counterpart Simon Newcomb in establishing an international standard for astronomical constants.

Downing died suddenly from heart disease on 8 December 1917,[2] in his home at 30 New Oxford Street, Bloomsbury.