[LEAPSECS] Look before you don't leap

[G Ashton]

Rob Seaman wrote, in part, on 20 May 2015 11:27 AM

>On the other hand the thing that calendars count are mean solar days.  It is precisely the “mean” part that permits calendars to sail unconcerned over daylight saving time adjustments and to ignore the red herring of the equation of time.  Universal Time meant mean solar time before UTC became coordinated.  And mean solar time now and forever will be an expression of the synodic day:

>	http://www.cacr.caltech.edu/futureofutc/preprints/files/28_AAS_13-515_Seaman.pdf

>If someone thinks otherwise then I suppose she must think a functional calendar could be made out of nothing but 23-hour “spring forward” days?

I think calendars count observed day/night cycles. Different cultures observe the transition from one day to the next at different points in the day, and change the transition point at various times without necessarily changing to a different calendar. Some cultures simultaneously observe different transition points for different purposes. For example, Friday afternoon an American Roman Catholic bank teller puts up a little sign in front of her teller workstation saying "I am on the next day's business". Saturday afternoon the same teller goes to Mass and fulfills her religious obligation to attend Mass on Sunday.

Mean solar time, of course, has nothing to do with daylight saving time.