Re: Possible re-entry of STEP-2 Pegasus deb(?)

Alan Pickup (
Sun, 10 May 1998 23:18:51 +0100

In message <>, Jeremy Nall
<> writes
>On May 7, while waitting for the now infamous Irid. 5 to flare (it was a
>no-show). I saw what might have been a re-entry event.
>At 21:07 CDT, it appeared at an RA & DEC of 12h 5m +9.0 deg. (approx.) and
>it moved due east. Initially as bright as Spica (alpha Virgo), it was
>visable for more than a minute to the naked eye. The declining light-curve
>was not smoothe, it appeared to "pulse" at about 1-2 second intervals.
>Alan Pickup's decay list #53 makes STEP-2 Pegasus deb (24423, 94-29 SB) a
>likely candidate. Although, I can find no other confirmation using SatSpy

The most recent elset for this object is from May 3:
Pegasus deb SB                                   500 x 439 km
1 24423U 94029SB  98123.24063980  .01156949  00000-0  33142-1 0  4987
2 24423  80.9133 188.8403 0043926  49.1868   4.3737 15.32173174215504
The drag value reported here implies decay on May 10 (today), a
conclusion which is reinforced by including in the analysis the four
other elsets issued over the preceding nine days. If no other elsets
materialise, this is the date which will appear as its "Actual?" decay
date in my next SatEvo decay list.

In any case, if I evolve the orbit to a decay at the time of the
observation (May 8 02:07 UTC), the orbital plane is ~25 deg too far to
the east, off the E coast of the US.

At least two other objects *did* decay on May 8:
   #    Designation    Name                  Estimated decay
 21057   91-  3 C   Italsat 1 Ariane r          May  8.23
 25333   98- 28 C   Echostar 4 Proton plat      May  8.69
 21895   92- 10 C   Superbird B1 Ariane r       May  8?
though there have been no elsets for the latter since April 28.

Both Arianes have inclinations of 6-7 deg, so would be too far S for
this re-entry. The Echostar launch was on May 7 at 23:45 UTC but all the
elsets for the platform (#25333, above) postdate the re-entry
observation, ruling this out too. If any uncatalogued objects from the
launch were re-entering at the time of the observation, they would have
been much too far to the W. I have also considered the possibility that
this was the decay of a debris object from the Long March launch of
Iridium 69, etc. Four such debris objects were catalogued, with two
(#25323 and #25326) decaying on the 6th and two (#25324 and #25325)
being apparently lost but probably decaying on a similar timescale.
Again, any decayers from this launch would have been too far to the W.

So, sorry, I cannot identify a suitable decayer for this observation.

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