NGC 3900 is an 11.3 magnitude spiral galaxy in far northeastern Leo. 7.4 magnitude HD 102646 marks the area about a degree to the north. Observing with the 10-inch Starfinder Newtonian at 129X, the galaxy appears elongated north-to-south, 3'x1' in size, with a stellar core region. A trio of faint GSC stars frames NGC 3900 along three sides. NGC 3912 is in the vicinity, just about 35' to the south.