De Vaucouleurs Atlas Type: SA(rs)c

Filter: B

Telescope: Pal 1.5-m
North right , East up
Field Dimensions: 3.9 x 2.9 arcminutes

RC3 Type: SA(rs)c
RSA Type: Sc(s)II
Surface Brightness Range Displayed: 19.5-27.0 mag per square arcsec
Absolute Blue Magnitude: -20.9

De Vaucouleurs Atlas Description:

NGC 6643 has two main arms which break from a region dominated by scattered knots. De Vaucouleurs (1959a) interpreted this region as an inner pseudoring and even assigned the galaxy an Sd type. The Sc type is preferred because of the relative smoothness of the outer arms and the signficant size of the core. In a 2MASS image (Jarrett et al. 2003), the region of the scattered knots takes on the form of a bright inner pseudoring .