Iridium 9 vs. 10

4 Mar 1998 16:30:06 -0800

Hi All,

Several people have contacted me concerning discrepancies between
the identifications of Iridium 9 and Iridium 10 as handled by IRIDFLAR
vs. SkyMap (and other programs).  SkyMap (and other tracking programs)
take the name line in the 2-line elements (i.e. line 0) literally.  =
name is there, the program will gleefully treat as gospel.  IRIDFLAR is
different, however.  It doesn't care what name is on the name line.  It =
has internally hard-coded names based on the 5-digit USSPACECOM catalogue =
number that appears in the TLEs.  Thus, if it sees #24839, it knows that
it's Iridium 9.  It is only when a new launch occurs with an unrecognized
USSPACECOM number that IRIDFLAR will turn to the name line for

The descrepany results when the TLEs have the wrong name on the name
line.  Some source out there in cyberspace, for example, has provided the
following TLEs:

IRIDIUM 10                                       779 x 776
1 24839U 97030D   98060.06583813  .00000012  00000-0 -26204-5 0  1267
2 24839  86.3970  55.3303 0002180  58.6330 301.5078 14.34217571 36745
IRIDIUM 09                                       781 x 774
1 24838U 97030C   98059.50135257  .00000008  00000-0 -41832-5 0  1403
2 24838  86.3946  55.4889 0004705  50.9466 309.2148 14.34217089 36654

These are WRONG.  I don't know what agency is responsible for continuing
to swap these designations, but I want people to be aware of the error.
One rumor is that the SEDS site (University of Arizona) is a culprit.  =
also heard that the Air Force Instititude of Technology at Wright-Patt =
have it wrong.  I choose to believe OIG, Mike McCants, Alan Pickup and
Ted Molczan, and they all say Iridium 9 is #24839, Iridium 10 is #24840.

If anyone knows of any web sites that have definitely got it wrong, could
they please post a message about it on Seesat?  Thanx!  --Rob