William Herschel discovered NGC 3726 = H II-730 = h910 on 5 Feb 1788 (sweep 808) and recorded "pB, bM, 4' long and 3' broad, r." His position is at the north edge of the galaxy. JH made two observations, first recording "pB; vL; E in meridian; vgbM; 4' l, 2' br; has a * at its northern extremity."

William Rambaut, observing with LdR on 26 Mar 1848, recorded "Before nebula came into the field of the large finding eyepiece Lord Rosse observed a vF neb p it about 2m nearly in the parallel [likely CGCG 242-042, which was ignored in the GC and NGC]. [NGC 3726] is tolerably bright nucleus almost in centre; Lord Rosse at intervals perceived traces of spiral arrangement; dark black elliptical stripe a little above the nucleus." R.J. Mitchell on 30 Mar 1856 wrote, "it appears of the shape annexed [sketch shows a dramatic "S" shaped (barred) spiral], which exaggerates. There can be no doubt of the bend upwards at Alpha [shows the southeast arm] and of the darkness about the nucleus." NGC 3726 was included in the list of spiral nebulae in the 1850 PT paper.

400/500mm - 17.5" (4/6/91): bright, large, oval 2:1 N-S, 5.0'x2.5', patchy mottled appearance, very small or stellar nucleus but no core. A mag 12 star is at the north tip 2.4' from the center. Member of the NGC 3877 subgroup with the NGC 3992 (M109) group.

900/1200mm - 48" (4/19/17): at 375x and 488x; very bright, very large spiral, extending 3:2 N-S, 4.5' or 5' x 3'. Contains a brighter, mottled central core that is sharply concentrated with an intensely bright roundish nucleus. Two obvious spiral arms are attached on the north and south end of the central region. The northern arm is brightest at its root near the northeast side of the core. It rotates clockwise and sharply curls west and southwest, then dims and ends west of the nucleus. This arm appeared a bit thicker than the DSS2 image. The southern arm is shoots straight southeast, and curls a bit east. The arm contains a couple of slightly brighter HII patches including NGC 3726:[BKB2006] 2, situated 1.4' south of center. The outer halo has a low surface brightness but extends to a mag 12.5 star 2.4' N of center.

Notes by Steve Gottlieb