De Vaucouleurs Atlas Type: SB(r)b
Telescope: NOT 2.5-m
North up , East left
Field Dimensions: 4.0 x 3.0 arcminutes
RC3 Type: SB(r)bc
RSA Type: SBb(r)I
Surface Brightness Range Displayed: 19.0-26.0 mag per square arcsec
Absolute Blue Magnitude: -21.5
Elmegreen Spiral Arm Class: AC 6
De Vaucouleurs Atlas Description:
The inner ring is a perfectly closed feature, different from NGC 1433 and NGC 3351 . The bar is very regular and smooth, while the outer arms are complex and multiple in number. The color index map shows that the ring and outer arms include recent star formation, but the map is misleading because closer inspection reveals that the south portion of the inner ring is not color enhanced compared to the north portion. This is why the nucleus appears miscentered within the blue star-forming ring. The color index map also shows that the bar region is completely devoid of any star formation and that no leading dust lanes are present. The absence of these lanes probably explains why the galaxy has no nuclear ring.
The deprojected image shows that the inner ring is intrinsically elongated along the bar axis. The intrinsic axis ratio of about 0.8 is typical of SB inner rings (Buta 1995). Although de Vaucouleurs adopted the classification of Sbc for NGC 2523 , we favor the Sb type because the arms have an intermediate degree of patchiness and openness, and because the bulge is significant. NGC 2523 is a barred spiral where Hubble's three classification criteria actually are reasonably consistent.