GEOSAT/ORBCOMM Prelaunch Elset

Ron Lee (ronlee@pcisys.net)
Sat, 07 Feb 1998 09:10:31 -0700

Geosat, 9 Feb 98, 15:01 UT
1 93333U 98-0xx A 98040.63577546  .00000050  00000-0  00000-0 0    12
2 93333 108.0420  47.1040 0011600 160.2750  14.9710 14.32000000    16

Note that there are some inconsistencies with this elset.   The info
provided to me is as follows:

                                    GEOSAT FOLLOW ON ORBCOMM SATELLIT
EPOCH (D/HH:MM:SS.SSS):             040/13:33:46.000 040/13:35:26.200
PERIOD (MIN):                        100.712          100.696        
INCLINATION (DEG):                  108.042          108.042         
ECCENTRICITY (DEG):                 0.001160         0.000985        
SEMI-MAJOR AXIS (KM):                7170.4727        7169.7039      
ARGUMENT OF PERIGEE (DEG):          160.275          175.190         
RA OF ASCENDING NODE (DEG):          47.104           47.104         
MEAN ANOMALY (DEG):                  14.971           12.624         
START ORBIT TIME (HHH:MM:SS.SSS)MET:000:14:31.000    000:16:11.200   
END ORBIT TIME (HHH:MM:SS.SSS)MET:  004:00:00.000    004:00:00.000   
HEIGHT (KM):                          788.4974         790.6399      
INJECTION LATITUDE (DEG):             4.40N            7.604S        
INJECTION LONGITUDE (DEG):          245.65E          241.322E        
INJECTION INERTIAL AZIMUTH (DEG):   198.086          198.195         
INJECTION TIME (D/HH:MM:SS.SSS):    040/13:33:46.000 040/13:35:26.200

The launch time is reported to be at 15:01 UT vice the 13:29 UT or so shown
here. In addition, the injection longitude from my elset is at 220.4 E vice
the 245.65 E shown above.   I believe the 245.65 E is incorrect for a 108 deg
inclination launch from Vandenberg.  

The launch window extends to 15:39 UT.

I made the elset for GEOSAT since the ORBCOMMS seem faint from my few obs.
However, during the initial early orbits, most of the objects should be
reasonably close.

Iridium and SNOE elsets to be posted later this weekend since those launches
are 11 and 13 Feb respectively.

As always, corrections and suggestions are welcome on my elset generation.
I typically use MAK2LINE to derive the initial elset, then run STSPLUS to
verify injection location and reasonableness of the elset.  Finally I run
ELEMAN to correct checksums.

Ron Lee