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Subject: Re: Ron's Answer re clock
From: Robert Fields
Reply To: mapug@shore.net
Date: Fri Jan 06 01:12:59 1995

The clock issue was discussed at length back in late October and Early November. This post, from the archives, does a good job at summarizing the situation. If your interested in the past conversation, which is remarkably similar to current conversation, check out the archives at the Netcom ftp site.

ftp ftp.netcom.com/pub/as/astrorcf/LX-200 ......

if this site is busy try:

ftp ftp2.netcom.com/pub/as/astrorcf/LX-200

-Robert astrorcf@netcom.com

On Sat, 5 Nov 1994, Ron Ezra wrote:

> The manuals have been changed to say setting the time may be necessary at
> each power up.
>
> The clock chip is there for only one reason - to display the local time.
> ALL other telescope functions (tracking, finding, alignment, etc.) is
> controlled by crystal, which is very accurate. We wanted to display
> local time, and a computer clock chip was the fastest (development time
> wise), easiest, and cheapest way to do it.
> As I think about this, there is ONE place that does use the local time. In
> the polar alignment routine, the local time is used to determine the
> position of Polaris - and hence sidereal. An error in local time will
> show up as an error in the position of the second alignment star. Once you
> center this second star and hit ENTER, then everything is updated to the
> actual second star position. So an error of one hour in local time would
> cause the LX200 to slew 15 degrees in RA off, but would correct
> everything when the second star is centered. Planetary postion is
> calculated on DATE only (it assumes mid-day, as I remember) - time is
> not used at all.
> The original manual said to have an accurate time, because, at the time, I
> wasn't sure how well the telescope was really going to point and I
> wanted to cover my **** .-) >

> Maybe I should add a line that makes it VERY clear that an accurate time is
> not required.
>
> :<Ron>
>
> (Didn't really mean to "flame" anyone...... well maybe I did a little <g>)
>