Re: Two definitions of LHA
From: Frank Reed
Date: 2017 Jun 2, 22:59 -0700
Mark Coady, you wrote:
"...ridiculously correcting lunars from UTC off my "atomic" clock watch to GMT proving that my engineering OCD far outweighs my common sense."
Ha! Your self-awareness overrules that OCD. But yes, that was some crazy shit ...before you figured it out! :)
And you wrote:
"UT1 is my understanding the closest match for true GMT"
Spot on. That time standard, UT1, is essentially the continuation of good old GMT apart from that twelve hour offset that occurred in 1925 (finally shifting zero hours of GMT from noon to midnight). That's why, when you go to the USNO web app that we all know and love --or should know and love-- here, it assures us that "the program assumes UT1".
Of other members of the UT family, you wrote:
"With a bunch of others...2, 3, 4, etc... just to confuse simple minds like mine..."
Yeah, none of those others matter, and most have been abandoned as irrelevant or redundant. The only flavor of UT we need to worry about are UTC, which progresses at an exact, physics-based, perfect rate, as nearly as we can implement with current technology, and UT1 which closely approximates UTC but adjusts to match the orientation of the Earth.