NGC 2903. - This galaxy has been observed by Burbidge et al. (1960a), who note a "hump" on the rotation curve along the northeast part of the major axis between 20" and 60" from the center. The only bright emission feature in this area is embedded in a broad dust lane which lies well inside of the luminous arm. Velocities in this arm show that it is approaching with a line-of-sight velocity of about 200 km s-1 while the interarm HII region is approaching with a velocity of only about 75 km s-1.
There can be little doubt that the eastern half of the galaxy is the near side; therefore, this galaxy is a fine example of a very open, two-arm spiral with trailing arms.
This galaxy is one of the group showing "hot spots" in the nucleus. The suggested identification of the nucleus of the galaxy is identified by a cross in the sketch. Other bright nuclear emission regions are also identified.