Oswald Thomas is commemorated by the Oswald-Thomas-Platz in Vienna, now the address of the Vienna Zeiss Planetarium.
In his 1934 book, Astronomie (Thomas 1934), he identified the missing Messier object M48 with NGC 2548, an identification which is now generally recognized, after T.F. Morris of RASC independently repeated it in 1959. Several historians have confused this identification of M48 with a presumed one of equally missing M47, but for this object, he has NGC 2478, the NGC number for Messier's wrong position, going back to John Herschel. The relavant lines in his book read (translated from German):
M-No. RA and Dec NGC-No. Constellation Object (1900.0)
.. 47 (7.50-15) 2478 Ship Argo Cluster 48 (8.09-06) 2548 Hydra Open Cluster ..