All about horizon and culmination settings

SatNOGS Software
1

i copy paste here, from #satnogs:matrix.org,

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fredy
Tbh I thought that there would be hardware limits to avoid any damage in stations, but this doesn’t seem to be the case. So, now we will have a soft and hard limits on both min horizon (elevation where the tracking of pass starts and ends) and min culmination (the min maximum elevation of the pass), I have some examples in the issue to make it more understandable how it will work.

me
can you give example . thank you

fredy
Ok let’s say we have 2 passes, all of them LEOP, so they start from 0 degrees, to max elevation and end up to 0 degrees:

Max elevation 10 degrees
Max elevation 40 degrees
Station with min horizon set to 5 and min culmination set to 15

a) Hard limits on both settings
pass 1 is not going to be scheduled (10 max elevation < 15 min culmination )
pass 2 is going to be scheduled, it will start from 5 degrees, to the max 40 degrees and back to 5 degrees (40 max elevation > 15 min culmination, the observation starts from/ends to hard min horizon 5)

b) Soft limits on both settings, observer set them to 0 (if not overwitten by observer see “a)”)
pass 1 is going to be scheduled, it will start from 0 degrees, to the max 10 degrees and back to 0 degrees (10 max elevation > 0 overwritten min culmination, the observation starts from/ends to overwritten min horizon 0)
pass 2 is going to be scheduled, it will start from 0 degrees, to the max 40 degrees and back to 0 degrees (40 max elevation > 0 overwritten min culmination, the observation starts from/ends to overwritten min horizon 0)

c) Hard limit on min horizon, soft limit on min culmination, observer set min culmination to 5 (if not overwitten by observer see “a)”)
pass 1 is going to be scheduled, it will start from 5 degrees, to the max 10 degrees and back to 5 degrees (10 max elevation > 5 overwritten min culmination, the observation starts from/ends to hard min horizon 5)
pass 2 is going to be scheduled, it will start from 5 degrees, to the max 40 degrees and back to 5 degrees (40 max elevation > 5 overwritten min culmination, the observation starts from/ends to hard min horizon 5)

d) Soft limit on min horizon, hard limit on min culmination, observer set min horizon to 2 (if not overwitten by observer see “a)”)
pass 1 is not going to be scheduled (10 max elevation < 15 min culmination )
pass 2 is going to be scheduled, it will start from 2 degrees, to the max 40 degrees and back to 2 degrees (40 max elevation > 15 min culmination, the observation starts from/ends to overwritten min horizon 2)

Two notes:
Note 1: Min culmination doesn’t make a lot of sense to be under min horizon as a value
Note 2: In case the pass based on the set parameters isn’t long enough (currently >2min) it will not be available for scheduling even if satisfies the limits

me
give me 24 hour. i should read it very slowly.
btw is it work for all station? or only latest satnogs-client ?

fredy
the limits are set and used in Network and not related with the satnogs-client
hm… we need to make sure what happens in case of hard limits and TLE changes, maybe we have a bug there, I’ll check it and come back. Maybe we should not update TLE in observations in case the station has hard limits set.

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@fredy so the hard limit checkbox actually to force / overwrite minimum horizon and culmination setting to all future observations

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Sorry, but every time I try to get my head around these settings, I get confused.

It starts with not understanding the relation between horizon and culmination, to be honest even after reading some explanations on culmination I can’t visualize it function/meaning.

Jan | PE0SAT

4

If you mean that when you change it in settings if it changes the already scheduled observations, no it doesn’t, you will need to re-schedule in such a case.

Indeed still it confuses me sometimes, in my plan is to add next to the settings a polar plot to visualize how this works.
It will have a 2-3 passes and dynamically will filter them when you change the settings and below will explain why the pass was filtered.

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