Xref: utzoo sci.astro:3570 comp.binaries.ibm.pc.d:2157
Path: utzoo!attcan!uunet!tektronix!percival!parsely!agora!rickc
From: rickc@agora.UUCP (Rick Coates)
Newsgroups: sci.astro,comp.binaries.ibm.pc.d
Subject: Re: planet.exe query
Summary: how it works...
Keywords: planet.exe
Message-ID: <1390@agora.UUCP>
Date: 2 Mar 89 22:07:48 GMT
References: <6528@ecsvax.UUCP>
Organization: Advanced Solutions, Hillsboro, OR
Lines: 58

In article <6528@ecsvax.UUCP>, jdmce@ecsvax.UUCP (Duncan McEwen) writes:
> 
> 
> Does anyone have experience with Rick Coates' planet.exe.  It was

Thanks. Should I post moon.exe and sun.exe?

> posted recently on comp.binaries.  I am delighted with the program
> but can't get the local time for rising and setting to work right.
> The numbers look ok when I default to the west coast, but when I
> input my own east coast LONG and LATI, the rising times don't make
> sense.
> 
> Supposedly, it is possible to insert an environment variable TZ=
> ones local time zone.  When I try TZ=EST it still doesn't work. 

This should be Unix standard... TZ=EST4EDT (I think - I've never had to
do it for the East Coast) The middle digit is what is important -
it is the number of hours west of GMT.

(I've actually never tested it for the east coast - let me know if
it doesn't work).

You can also use the command line argument to set latitude and longitude.
> Any suggestions.
> 
> I would also appreciate it if an astronomer would help me distinguish
> between geo and topocentric equatorial positions.  

(I'm not an astronomer, but...)
Not much difference at all for planets - but there will be for the moon
program.  Geocentric is for an observer at the center of the earth;
topocentric is for where you are on the surface of the earth.

> 
> I'm also curious to know what an hour-angle is.

Astronomy has all sorts of ways of describing positions.  Hour-angle is
the angular distance from 'straight up' where and when you are. 
An hour angle of 0 is straight up.

> 
> One last question.  Would someone care to explain how azinmuth is defined.
> 

Azimuth is the angular distance (usually, and in the case of my planet program)
from due north clockwise. Elevation is how high in the sky the object is.

> Thanks in advance.


Please forgive any dumb mistakes I might have made in my explantion.



Rick Coates

tektronix!reed!percival!agora!rickc