NGC 3521 es una fantástica galaxia espiral del tipo M 63, situada en la constelación de Leo a unos 35 millones de años luz de nosotros.
Su magnitud es la 10ª y sus dimensiones aparentes de 12 x 6 arcmin.
Sin embargo no es un objeto frecuentemente observado ni fotografiado por aficionados, quizá debido a que está en una zona despoblada de estrellas brillantes de referencia y que más hacia el norte hay otras galaxias igualmente grandes y brillantes como M65 y 66, M95 y 96...
Como curiosidad decir que el ecuador celeste pasa justamente sobre ella.

NGC 3521 is a truly fantastic spiral galaxy (of M 63 type), located in the constellation of Leo at some 35 mio L.Y. away from us.
It shines brightly at 10th mg. and its apparent size is 12 x 6 arcmin.
However despite of that , it is not a frecuently observed or photographed object by amateurs, perhaps due to the facts that the field where is located is devoided of bright reference stars and nearby northwards there are some other large and bright galaxies like M65 and 66, M95 and 96... that would rival with it
As a curiosity, there is the fact that the celestial equator crosses the main body of the galaxy.