R.J. Mitchell discovered NGC 4637 on 1 Mar 1854 using LdR's 72" and recorded a "Double nebula [including II-70 = NGC 4638], faint nebulosity connects them." No comment was made on the relative brightnesses or orientation and there were no further observations at Birr Castle or by any others. RNGC identifies NGC 4637 with an extremely faint spindle-shaped galaxy just following NGC 4638. Although this is identification is reasonable (repeated by Carlson), the RNGC magnitude of 12.0 is greatly in error and the identifications of NGC 4637/4638 are reversed in MCG.

But Dreyer comments in the NGC notes "It is very possible that the Birr observer mistook M60 and III 44 [NGC 4647] for h1402 and a nova." In his photographic survey "Die Herschel Nebel", Karl Reinmuth notes "not found, =[NGC 4647?" Adelaide Ames also states "not found" in the Virgo-Coma Survey at Harvard College Observatory, Vol 88, No 1. See Harold Corwin's identification notes for further analysis but the identification of NGC 4637 is uncertain - either applying to the faint companion of NGC 4638 or the companion of M60.

600/800mm - 24" (5/25/14): at 225x, this companion to NGC 4638 appeared extremely faint, fairly small, elongated 5:2 E-W, ~25"x10". Required averted vision and could not hold for fairly brief intervals. Located 1.6' E of the center of NGC 4638. The identification of this number is uncertain and it may be a duplicate of NGC 4647

Notes by Steve Gottlieb