Re: Initial GoTo In APCC Pro Cause Nose or Tail Dive

Dale Ghent

On Dec 23, 2020, at 21:29, John <> wrote:

I thought the offset for the Pacific time zone is UTC -8 China is UTC +8 I'm not sure why the powers to be started using UTC instead of GMT (as in GMT -8). Doesn't the offset convert
Universal Time Coordinated (UTC) to my Pacific local If it's 2200 in Greenwich England, than it is 2200 - 8.00 hrs or 1400 here in NV... UTC -7 during the summer Thanks!
Yes, GMT offset is negative to the west, so you are correct there.

UTC and GMT are indeed equivalent, and it might be confusing why both exist when on the surface they seem to be the same thing. But there is a subtle yet important difference - GMT is an actual time zone, where UTC is not. Time zones are the equivalent of political boundaries, but for time. They can change, they are mutable as political, cultural, or other human wants dictate. UTC will always be UTC. It is a fixed, universal time coordinate. Right now, UTC and GMT are the same time reference. It might be in the future that the definition of GMT could change for whatever reason and, if that comes to pass, UTC clocks won't care while things that are pegged to GMT might.

(Modern) Computer clocks run on UTC time. It is the operating system's timezone database that is what converts the UTC time to the local time, general for presentation for the user. Whenever a political whim changes the definition of a time zone, that database needs to be updated lest the users in the affected time zone(s) start seeing the wrong local time. It can see many such changes in a year and why it's impractical for such a database to be included in something like the mount hand controller. Tracking and issuing hand controller firmware updates would be a major time sink, not to mention the amount of limited storage space it would consume to the exclusion of more useful code.

If you're always using your mount with ASCOM/APCC, but still want to use the keypad, then just set the keypad's auto-connect parameter to EXT. This will cause the keypad to NOT be the initializer of the mount and defer to an EXTernal thing to do that job, such as the A-P ASCOM driver or APCC. If your computer's clock is correct and you have the proper timezone specified for under your site's configuration in APCC, then you will not have to worry about manually updating your mount's notion of what local time it is.


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