Harold Corwin

IC 3589 is a star just north-preceding IC 3591. Schwassmann has the following data (equinox 1900.0) for these two objects:

               Working
      Running   Number
      Number  On Plates
Object   Sn     (Sn)   Zone       RA           Dec        Desc

I3589   29       7     Ia2   12 31 56.23   +07 29 13.2   vF, pS, R, li *
I3591   30       6     Ia2   12 31 57.99   +07 28 35.0   F, pS
                47     II3   12 31 58.24   +07 28 36.3   F, cS, nr * 14,
                                                          alpha, delta:

Note that IC 3589 was picked up in only one zone of the two that Schwassmann searched across this area.

If we adopt 12 31 58.07 +07 28 35.4 for IC 3591 (half weight for the 2nd position which is noted uncertain) then the differential position with respect to IC 3589 is 27.4 arcsec in RA and -37.8 arcsec in Dec. Measured on the Sandage-Binggeli photo in their Paper III (Plate 52, p. 1095, AJ xx, 198x), the difference in position between the galaxy and the brighter star to the upper right is 26 arcsec in RA and -34 arcsec in Dec. Within the errors of my measurements (a few arcsec), the offsets agree, so IC 3589 is certainly the star.

― IC Notes by Harold Corwin