A study by Brian G. Marsden in 1967 was the first attempt to trace back the orbital history of the group to identify the progenitor comet. All known members of the group up until 1965 had almost identical orbital inclinations at about 144°, as well as very similar values for the longitude of perihelion at 280–282°, with a couple of outlying points probably due to uncertain orbital calculations. A greater range of values existed for the argument of perihelion and longitude of the ascending node.