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*To*: tass@listserv.wwa.com*Subject*: No Escape*From*: Tom Droege <tdroege@veriomail.com>*Date*: Sun, 11 Mar 2001 17:33:58 -0600*Delivery-Date*: Sun Mar 11 18:32:40 2001*Sender*: owner-tass@listserv.wwa.com

From some things there is no escape. Cary Chieborad gave me a formula for calculating the juliandate and the modified julian day? Jure says it is day, but Cary's document says date. Looks like MJD is what I want as it agrees with the Julian Day that people have sent me. I am now trying to get at the zenith RA so that I can calculate where the telescope is pointing. Jure suggested using the known Julian Day for Jan 0.0 2001 which Doug's formula required, and correcting with the fractional MJD for the current time. Starting to do this, it is obvious that Cary's forumla needs UT and not local time. This even though the variables are named things like: local->tm_year, local->tm_mday. OK, so I have set out to convert local time to UT. Ug! You don't get off easy. Once you subtract 6 hours (or whatever time zone you are in) This requires correction for the number of days in the month through the full leap year process. Let's see, I think it is all years divisible by 4 are leap years except those ending in 00? That should be good enough. Hmmm! Possibly the right way to do it is to just use Cary's formula as if one lived in Greenwich, then subtract the 6 hours from the result. Somewhere there must be a reference page that I can look at that has algorithms for all these things? Can anyone point me to one? It is senseless for me to compute them all from scratch when someone somewhere has done it right! OK, don't think you all are going to get off easy as I struggle with this. I will do the best I can, then put everything I use up for criticism. Then we all will get to live with the result. Tom Droege

**Follow-Ups**:**Re: No Escape***From:*Cary Chleborad <bennu@ns.net>

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