On Apr 19, 10:32*pm, Difei wrote:
Greetings all,
My question is how can I calculate the JDEs corresponding to other
apparent longitudes, say, 15, 30, 45, 60 degrees, etc. Any idea would
be helpful, thanks in advance.

Difei,
It is *very* difficult to cherrypick your way
through Meuss to find specific 'ad hoc'
calculations that you may need for any observations,
projects etc. Some things you may be able to
get from JPL Horizons http://ssd.jpl.nasa.gov/horizons.cgi
or from the Harvard MPL.
http://www.minorplanetcenter.net/iau/MPEph/MPEph.html

I would suggest that you byte the bullet and reconcile
yourself to the fact that you are going to have to do
your very own Excel spreadsheet. This is because
Meeus is constantly referring you back to earlier
chapters and this is a pain "ol wazoo". But Meeus is
addictive and once you start getting the terms in place
you will want to keep after it. In spite of the fact that
'Astronomical Algorithms' comes from the Golden Age
of desktop computing (Basic, Quick Basic etc) it lends
itself to spreadsheet calculation readily.

If you don't have Excel you can get it in "Open Office"
for free. If you don't know how to operate in Excel
you can learn it by doing the calculations in
"Astronomical Algorithms". ( I did.)

So do you have Excel?

Ben