It sounds like this was very likely the failed 2nd stage burn of the IUS on the Titan 4 DSP/IUS launch which was witnessed. I suspect the Titan 4 left the DSP/IUS in a LEO. The first stage burn would have taken place shortly after the 1701 UTC launch. This would have put the spacecraft in a transfer orbit to geostationary orbit which would be a 12 hour orbit. Thus it takes 6 hours to get to geo altitude which would be on the order of 2300 UTC (ie 6 hours after launch). The time of 2330 would nicely agree with this time line. The IUS first stage did not cleanly separate from the second stage and caused the upper stage to tumble during the burn. This would have caused the plume to be much larger than normal. Bill Bard Ron Lee <firstname.lastname@example.org> on 09/09/99 10:46:31 PM To: SeeSat-L@blackadder.lmsal.com cc: (bcc: Bill T Bard/STP/Raytheon/US) Subject: Re: HELP: Strange cloud back in April. A Titan/IUS was launched on 9 April at 1701 UT from Florida. I have never seen a solid rocket burn but it is at the top of my wish list. Well, maybe second after seeing a re-entry of a rocket or payload that breaks up. I suspect that a solid rocket would eject particulate matter that, if sunlit, might behave as you described. I will take this chance to once again plead, beg, and whimper for advance notice of any solid rocket burn (geosynchronous is fine). Ron Lee Amateur astronomers and >general public as well observed from Sao Carlos, Brazil (22 deg 01' S, >47 deg 54' W, elevation 850 m) the apparition of a strange ball-like >white cloud on Friday April 9, 1999 at aproximatelly 23:30 UTC (20:30 >local). The small round cloud appeared at about 28 deg Alt, 290 deg Az >(in Orion, between the "Orion Belt" and Betelgeuse), grew larger and >turned into a smoky ring of a diameter of about 3-5 deg. It lasted about >5 min and appeared to remain fixed related to stars in the background. >Other people observed the same phenomenon from nearby cities (including >Bauru, 140 km SW) at roughly the same time and in the same part of the >sky. We have no explanation so far. Could it had been generated by a >Titan 4 rocket (or its payload) launched on that day?. Or by an Ariane >42 (or payload INSAT 2E) launched a few days earlier?. Were phenomena >like this one observed before?. > Aldo Loup.