In Messier's List M 25 is also the magnitude 4 open cluster located 2,000 light years away at R.A. 18:16.9 and Dec. -18°29, between the head & the end of the bow of the constellation Sagittarius. M 25 contains over 100 stars, and is about 23 light years across.

The cluster also contains one bright Cepheid variable, U Sagittarii which fluctuates from 6.3 to 7.1 magnitude over a period of 6.75 days.