Unid Geosync Flasher
Richard Baldridge (rbaldridge@LittonSolidState.com)
Mon, 19 Oct 1998 07:38:00 -0700
I've observed this interesting object now on four consecutive nights.
It is following almost the same path each night relative to the stars,
indicating a sidereal rotation rate (Mean Motion close to 1.000). It
has been entering into the Earth's shadow about 6:45 UT. The track is
currently taking the satellite near Jupiter for parts of the USA.
Some flashes are close to 6th magnitude or slightly brighter, although
they come at infrequent intervals. Typical flashes are 8th - 10th mag
about every 5-10 seconds with some rapid, multiple flashes observed. I
observe with a 12.5" f7 Newtonian. The satellite is generally not
observable between flashes, so scan slowly if you're out looking for it.
The following positions are available, accurate to +/- 13" of arc RA and
+/- 6" arc Declination, (greater error in RA due to timing error and
being able to see a "flash" near a star conjunction. All times and
dates U.T.
Oct 17 4:24:36 UT 22h48m32.5s -13.1016
Oct 17 5:54:19 UT 0h14m37.1s -6.6529
Oct 17 6:32:54 UT 0h51m27.3s -3.7652
Oct 18 6:30:11 UT 0h45m23.5s -4.1641
Oct 19 4:31:11 UT 22h47m53.9s -13.0376
Observing position: N37.2718 W121.9770 Alt 72 Meters
I do not have a good orbit determination program or the skill to do an
orbit fit myself. Mike McCants sent some very helpful elements based on
my original (but sloppy) data points. Taking his elements, I was able
to locate the satellite again and "messaged" the elements to arrive at
the following elset. This set fits three days of observations fairly
well, (within about 0.2 degree -- good enough to find the object again
for the near-term). Please note that the checksum on line 2 is probably
in error.
Unknown
1 98003U 98289.25055645 .00000000 00000-0 00000+0 0 00
2 98003 15.1000 4.4195 0001000 .0240 359.9800 0.99799244 02
I arrived at the Mean Motion by plotting the moment when the satellite
crossed the -4 degree Declination line on two consecutive nights. These
were:
Oct 17 11:29:50.5 UT +/- 2 seconds
Oct 18 11:32:09.4 UT +/- 3 seconds
This gives one rev in 24.0385 hours, or .99839 revs/day. However, this
did not match the observed path exactly for some reason, so I again
messaged the MM to the above elset value.
The inclination is probably a bit off, but fits the observations fairly
well from -13 to -3 degrees declination as observed from my position, a
fair length of observed acsending arc of the orbit. Eccentricity is a
guess only.
I'd appreciate anyone doing a better elset fit to the positions above.
Thanks.
---- Rick Baldridge rbaldridge@littonssd.com