It’s my experience with my arduino based tracker that the TLEs age rapidly and must be refreshed on game day.

I attributed this to the single precision math although it could be due to some more fundamental misunderstanding on my part.

Now that there are no more shuttle re-supply flights even ISS reboosts are fairly infrequent.

I am using the most excellent qrpTracker library (Bruce Robertson VE9QRP) which is in turn derived from PLAN13 (James Miller G3RUH).

https://youtu.be/VG5L5oP2uNk

https://github.com/twdeckard/AE-35/blob/master/sketch_ae-35/sketch_ae-35.ino

Best Todd

Sent from my iPhone

On May 12, 2018, at 6:21 PM, Alfredos (fredy) Damkalis fredy@fredy.gr wrote:

Recently it was posted in libre.space community discourse[1] by cgbsat an interesting analysis about TLE of a couple of satellites and what delays you should expect in observation starting time when you use TLE 0-10 days old.

Delays vary depending on satellite, difference could be from some seconds to some minutes (in ISS case).

I'm very interested if there are similar analyses.

73, fredy

[1] https://community.libre.space/t/tle-updates-and-scheduling/1987/4

...

On 05/12/2018 08:02 PM, Ron VE8RT wrote: I understand that there won't be a good answer for how old can TLE's be before they're of no use. If you were going to be offline for an extended period, roughly, for a LEO, how long would you go before they're worthless?

Ron VE8RT