RE: NROL-55 sighting (maneuvering)

From: Ted Molczan via Seesat-l <>
Date: Sun, 11 Oct 2015 08:54:17 -0400
Spaceweather has images taken from Tibet and Iran:

The image from Tibet is a 5 s exposure beginning at 14:07:38 UTC. The lower, solid streak was left by the NOSS
payloads. The upper, bright streak is the Centaur that deployed the NOSS into their 63.4 deg, 1100 x 1200 km orbit. The
Centaur appears to have been in the midst of the first of two burns to manoeuvre to the 64.8 deg, 481 X 782 km Cubesat
deployment orbit.

The first burn was expected to occur near the time photo was taken, while the Centaur was in the vicinity of the first
apogee after launch. It lowered the perigee to 481 km, creating a temporary 481 X 1200 km orbit. It probably also
changed the inclination and argument of perigee.

The second burn occurred about 65 min. later, when the Centaur arrived at the new perigee. There, it lowered its apogee
to 782 km, resulting in the final 481 x 782 km orbit. That burn is not in either photo.

The image from Iran is a 30 s exposure beginning at 15:45:35 UTC, which was about 45 min. after the final Centaur burn,
and 10 min. before the first Cubesat was deployed. The solid track is the Centaur. The wide, nebulous streak is the
plume from the Centaur's fuel dump, which probably was completed a short time before the photo was taken.

Ted Molczan

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Received on Sun Oct 11 2015 - 07:54:58 UTC

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