mailing list bounced my pedantic response due to attached image size ...

here’s a link to a parallel thread that has the image of ISS altitude over time.

http://forums.qrz.com/index.php?threads/need-help-with-ascending-node.549308...

Sent from my iPhone

On May 19, 2018, at 6:43 AM, Todd W Deckard twdeckard@earthlink.net wrote:

As an aside, the ISS makes an adjustment approximately once a month. They operate at a higher altitude now that the shuttle is no longer used for resupply. Here is a plot from heavens-above.

<image1.png>

I have observed that if you are using an Arduino or another processor with single precision math, the computed results age very quickly for any LEO and practically I must update every few days.

if you are using a more respectable math engine and are only concerned about the orbital elements; the error in the satellite position is approximately a kilometer at the epoch of the TLE. Then the simplified perturbation model (SPG4) used by the common software we use loses about 1-2km a day.

all of this is a bit pedantic if you are hand pointing an antenna in the noble tradition ...

best Todd Sent from my iPhone

...

On May 18, 2018, at 9:51 PM, amsat-bb-request@amsat.org wrote:

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