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AO-40 Attitude Information
- Subject: [amsat-bb] AO-40 Attitude Information
- From: Peter Guelzow <peter.guelzow@xxxxxxxxxxxx>
- Date: Sat, 29 Dec 2001 17:02:45 +0000
Dear All,
May I take this chance to say a big thank you to our command stations
James Miller G3RUH, Stacey Mills W4SM, Ian Ashley ZL1AOX, Graham
Ratcliff VK5AGR, and all those who support them with telemetry, for
an outstanding effort in keeping AO-40 operational and work as it's best.
Special thanks also to Paul Willmott for keeping the telemetry archive
up to date and organizing all the mass of telemetry data.
HAPPY NEW YEAR to everyone!!
best wishes
Peter
--
Peter Guelzow, DB2OS
Pres. AMSAT-DL
The following information is provided by G3RUH:
______________________________________________________________________________
AO-40 Attitude Information
--------------------------
The YACE camera was activated on Orbit 535 in order to check the AO-40
attitude.
This is done every 5 orbits which also enables calibration of the excess
precession in ALON (the so-called "Mystery Effect").
Presently the Sun sensors cannot see the Sun, so the Sun/Earth sensor system
is unuseable. This "hibernation" commenced on orbit 529 (Dec 24) and will
continue until orbit 549 on 2002 Jan 09 [Wed]. You can tell that this is the
case because the telemetered analogue spin rate is meaningless; the true
spin rate is in fact 2.51 rpm.
Today Dec 29 on orbit 535 the attitude measured ALON 327.4, ALAT -11.4
with an uncertainty of order 0.1 deg.
The attitude direction will drift as follows:
Sun Illumin-
DATE ALON ALAT Angle ation %
---------------------------------------------------
2001 Dec 20 [Thu] 347.5 -10.2 -37.2 79.7
2001 Dec 21 [Fri] 345.7 -10.2 -39.0 77.7
2001 Dec 22 [Sat] 342.2 -10.2 -41.8 74.5
2001 Dec 23 [Sun] 340.3 -10.3 -43.5 72.5
2001 Dec 24 [Mon] 338.5 -10.3 -45.1 70.6 << Sun sensor stopped
2001 Dec 25 [Tue] 336.6 -10.3 -46.5 68.8 .. .. ..
2001 Dec 26 [Wed] 333.1 -10.3 -48.6 66.2 .. .. ..
2001 Dec 27 [Thu] 331.3 -10.3 -49.7 64.7 .. .. ..
2001 Dec 28 [Fri] 329.5 -10.4 -50.7 63.4 .. .. ..
2001 Dec 29 [Sat] 327.6 -10.4 -51.5 62.3 .. .. ..
2001 Dec 30 [Sun] 324.1 -10.4 -52.3 61.1 .. .. ..
2001 Dec 31 [Mon] 322.3 -10.4 -52.7 60.6 .. .. ..
2002 Jan 01 [Tue] 320.4 -10.4 -52.9 60.4 .. .. ..
2002 Jan 02 [Wed] 318.6 -10.4 -52.8 60.4 .. .. ..
2002 Jan 03 [Thu] 315.1 -10.5 -52.3 61.2 .. .. ..
2002 Jan 04 [Fri] 313.2 -10.5 -51.8 61.9 .. .. ..
2002 Jan 05 [Sat] 311.4 -10.5 -51.1 62.8 .. .. ..
2002 Jan 06 [Sun] 309.6 -10.5 -50.2 64.0 .. .. ..
2002 Jan 07 [Mon] 306.1 -10.5 -48.4 66.4 .. .. ..
2002 Jan 08 [Tue] 304.2 -10.6 -47.2 68.0 .. .. ..
2002 Jan 09 [Wed] 302.4 -10.6 -45.8 69.7 << Sun sensor restarts
2002 Jan 10 [Thu] 300.5 -10.6 -44.3 71.5
..
---------------------------------------------------
On Jan 09, when the Sun sensor recovers lock, the magnetorquer will be used
once again to:
a) counteract the "mystery effect" precession (drift) in alon
b) to drive alat towards alat=0
c) increase alon towards alon=360 as rapidly as the Sun's movement allows.
Broadly the future should be:
Date Alon Alat
-----------------------
2002 Jan 08 300 -10
2002 Jan 15 300 -5
2002 Jan 22 300 0
2002 Feb 19 320 0
2002 Mar 19 340 0
2002 Apr 13 360 0
-----------------------
Excellent communications are available now, and will be maintained throughout
this period.
JRM 2001 Dec 29 [Sat] 1414 utc
______________________________________________________________________________
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