Hi Les,
I believe the last set of elements published in
MPEC 2011-M31 to be erroneous. This was noted by a number of people in one of the recent comet lists. Apparently, the elements are auto generated now, so something must have gone amiss.
Interesting when I use the same astrometric sets I have consistently being getting perihelion around March 11 from the past 2 weeks so wonder if there is still a minor problem with the elements given in the recent circular. In any case it does make too much difference in viewing circumstances.
Terry