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Re: AO-40 MA, ALON/ALAT and squint angle ??

Hi Mike,

I think you're correct.  I've been using a figure of -2.2,81 in IT, and the
results seem believable.

As explained by someone else earlier, you have to change the sign of the
ALON, and take the backbearing of the ALAT (ie add or subtract 180 degrees
to arrive at a new value within the range 0..359 degrees), because the
high-gain antennas on AO-40 are on same side of the satellite as the 400N
motor, whereas they were on the opposite side of the satellite on AO-10 and

(I was going to use the terms -z and +z facet, but found some
inconsistencies in geometrical descriptions of the satellites while putting
this email together.   Hmmm, more later).

You're correct that if the satellite's ALON/ALAT is 2,260, then we should
enter that into IT as -2, 80.

(This must be confusing to newcomers!  Pity we didn't catch this when
beta-testing the software).


Chris vk6kch

At 18:48 30/12/2000 EST, you wrote:
>In a message dated 12/30/00 6:18:15 PM Eastern Standard Time, 
>cbuttsch@slonet.org writes:
>> If you are using InstantTrack 1.5 attitude must be entered as  2,260
>>  It is very easy to reverse these but latitude is firs, then a comma,
>>  then longitude.   (Page 23 of the instruction manual)
>Doesn't this have to be entered as -2,80 because IT 1.5 uses the AO-13
>calculations that has the antennas on the reverse side that AO-40 does??
>I know NOVA for Win calculates squint correctly for AO-40 for both hi-gains 
>and omnis. Mike recoded this. IT 1.5 matches NOVA is I use -2,80.
>Mike, N1JEZ
>AMSAT #29649
>Local Area Coordinator
>"A closed mouth gathers no feet."
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