plotting tracks and markers on a map

[Roelof Burger <roelof@xxxxxxxxxxxxxxxxx>]

Dear ferreters,

I have:

name     title                             I         J         K         L
GLAT     GPS Lattitude                    ...       ...       ...       1:5360
GLON     GPS Longitude                    ...       ...       ...       1:5360

where L is seconds since basetime - time coordinate variable is:
   
    int time(time) ;
                time:long_name = "Seconds since base_time" ;
                time:point_spacing = "even" ;
                time:time_origin = "28-JAN-1999:14:02:39" ;
                time:units = "sec" ;

I want:
a nice chart of Southern Africa "region - 40S to 10S and 10E to 40E"
with the flight path plotted on it.

this i can do with:

yes? plot/ylimits=-40:-10/xlimits=10:40/vs GLON,GLAT
yes? go land

[but i don't really like to specify the y and xlimits - i would prefer to
specify the region (set region) but can't make it work. because the axis is then
numerical and not lat/lon - eg. -10 and not 10S]

then i want to plot a point on the map - (say 28E and 28S)
this i can't do with:

yes? plot/vs/over/symb=3/line=5 y[y=28s],x[x=28e]
 **ERROR: illegal limits: Y is not in the range Y=-28
          Axis extremes are Y=0.5:10000000

to get this working i have to say:
yes? define axis/X=10:40:10/unit=DEGREE xlon
yes? define axis/Y=-10:-40:10/unit=DEGREE ylat
yes? define grid/Y=ylat/X=xlon xyaxis
yes? set grid xyaxis

(i don't understand why it doesn't work to do:
yes? set region/y=40s:10s/x=10e:40e )

so - no **ERROR but now symbol as well (on my map that is)
remember the axis is numerical

what i need:
1. answer to problem of specifying region for map other than x/ylimits
2. axis in degrees S etc
3. how to plot a point on the map

ALSO the coastline at the point of africa 19E (cape augulus) has a break - maybe
due to our ferret masters cutting africa in half with the basemap? can this be
fixed ?

i will appreciate help very much
have a great day
roelof

-- 
Roelof Burger                  tel  : +27-58-303-5571
SAWB / Metsys                  fax  : +27-58-303-2352
P/Bag X15 Bethlehem 9700       email: roelof@metsys.ofs.gov.za
South Africa                   www  : http://metsys.ofs.gov.za/