MUOS 5 brightness variation

From: Marco Langbroek via Seesat-l <seesat-l_at_satobs.org>
Date: Thu, 7 Jul 2016 15:18:50 +0200
Yesterday I communicated observations of MUOS 5 (2016-041A) in GTO:

http://www.satobs.org/seesat/Jul-2016/0014.html

I noted in my report that it showed a "a marked brightness variation". Imagery 
of that brightness variation is here:

http://sattrackcam.blogspot.nl/2016/07/tracking-muos-5.html

By looking through my image series from Jul 4-5, I found a periodicity of ~5.0 
minutes peak-to-peak. Peak brightness I estimate to be in the order of mag +8 to 
+9. The brief peaks are short and somewhat variable in duration: it rises and 
fades in less than 30 seconds to less than ~1 minute.  During minima, the 
satellite was invisible (note: observations were done in a light-polluted sky 
with the satellite at only 14-16 degrees above the horizon, and variable sky 
conditions)

Approximate times of brightness peaks (accurate to ~30 seconds), from imagery 
with a 1.4/85mm lens and exposures of 10 to 15 seconds (depending on conditions):

TIME  (UT, July 4-5)
23:40:45
23:45:50
23:51:00
[break from cloud field]
00:10:55
[break from cloud field]
00:25:55
00:30:40
00:35:55
00:40:30
00:45:55

The ~5.0 minute periodicity is well discernable.

- Marco


-----
Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
e-mail: sattrackcam_at_langbroek.org

Cospar 4353 (Leiden):   52.15412 N, 4.49081 E (WGS84), +0 m ASL
Station (b)log: http://sattrackcam.blogspot.com
Twitter: _at_Marco_Langbroek
-----
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Received on Thu Jul 07 2016 - 08:19:31 UTC

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