NGC 6118 (the Blinking Galaxy) proved to be quite a bear for me from two locations in south central Pennsylvania. It was definitely the most difficult object on the Herschel 400 list, at least initially. I was unable to see it using the orange zone Naylor Observatory's 17" classical Cassegrain despite repeated attempts and a friend's 20" classical Cassegrain at a darker site. However, under the dark skies of Stellafane I finally logged it using an 8" Newtonian belonging to none other than Phil Harrington.
I believe the Astronomical League originally advised that a six-inch aperture, in good conditions, was sufficient to find all the objects on the Herschel-400 list, and they have all been found in much smaller apertures, as small as 55 mm.
Clear sky ...
