MegaStar version 4.0.26 has this object plotted incorrectly, about 6' west of the actual position. The correct coordinates are given above. You'll find NGC 2129 about 40' due west of 4.2 magnitude 1 Geminorum. The sketch at left presents the cluster's appearance in my 10-inch Newtonian at 129X. The 6.7 magnitude cluster is centered. An isosceles triangle asterism lies at its heart. This organization includes 7.4 magnitude HD 250290 at the apex of the triangle and 8.2 magnitude HD 250289 about 10' due north occupying the west end of the short side. Another 15 stars at the center of the sketch are cluster members. The outlying 16 field stars frame the view. While in the area, look for NGC 2158 near impressive M35. They're just 2 degrees to the northeast.