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Re: Further AO-10 Observations On Perigee Passes



At 08:44 AM 10/22/1999 EDT, K5OE@aol.com wrote:
>I have been causally timing the QSB during perigee passes and note a 
>semi-consistant pattern of about a 14 minute cycle:  8 minutes of
discernible 
>audio going from "barely there," through the "warble" stage, on up to about 
>S5 signals, and then back down again.  The progression appears fairly
linear, 
>but I took no quantitative readings.  The 5-to-6 minute fade is, as reported 
>by the ops in the UK, complete--absolutely nothing heard from the
transponder 
>for this period, although I could discern the beacon even in the deepest
part 
>of the fade.  
>
>This behavior is important to note, because if you listen for AO-10 and
don't 
>hear anything, it may just be a fade.  Wait a few minutes and keep trying
the 
>transponder.  When the signals pop up, talk fast :-))
>
>The perigee pass tonight over the southern US and all of S.A. is 0002 - 0026 
>UTC.
>73,
>Jerry, K5OE
>

AO-10 currently experiences eclipses at perigee of approximately 30 minutes
length.  The one tonight should start at 00:37:34 UTC (MA = 255) and end at
01:07:08 UTC (MA = 30).  During this time there should be complete loss of
signal.  What Jerry is describing above appears to be a different
phenomenon related to slow tumbling of the satellite producing poor
illumination of the solar panels, poor antenna positioning, or both.
However, please note that the perigee eclipses will continue for a long
time (months). They will slowly move towards a later period in the orbit
and a corresponding longer duration into the early part of 2000. For
example, by 2000/03/01, the eclipses will have moved to MA 45-72 and will
be 75 minutes long.  AO-10 won't be "eclipse free" again until March 25, 2000.



-- 
____________________________________________________________________
Stacey E. Mills, M.D.  WEB:  http://www.people.virginia.edu/~sem2r/
Charlottesville, VA    E-Mail: sem2r@virginia.edu or w4sm@cstone.net  
			     Office Phone: 804-982-4406  Fax: 804-924-8767
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