Nico- Thanks for adding additional clarity to this somewhat murky process! -David, N9KT
On Sat, Dec 14, 2024 at 10:22 AM Nico Janssen hamsat@xs4all.nl wrote:
David,
Let me elaborate a bit on Joe's great comments.
The source of the TLEs in the Satellite Catalog (SatCat) is the 18thSDS. They publish only the TLEs of non-classified objects through Space-Track.org, which is the interface between the 18thSDS and 'the outside world'. The TLEs for classified objects are generated and published by amateur observers.
For some reason many people continue to use the name NORAD when referring to the SatCat. But NORAD has NOT been involved in the SatCat since the early seventies of the previous century. Since that time several other military organizations have been responsible for the maintenance of the SatCat. Currently it is the 18thSDS. The unique identification numbers for the objects in the SatCat are called Catalog Numbers (CatNr), so not NORAD Numbers. Some other names are also used, e.g. Object Numbers or, more recently, Satellite Numbers (SatNo). But that last name suggests that the objects are always satellites, while of course they can be Rocket Bodies (R/B) or pieces of debris. So again, the name NORAD does NOT apply. Best to remove that word completely from your vocabulary ;-) .
Another misunderstanding is that the 18thSDS identifies new satellites after their launch. That is not what happens. In the radar tracking network they can only see 'blips' on their radar screens. But they can not tell which blip belongs to which satellite. They can generate TLEs for all the observed objects without knowing which satellites are involved. So they depend on outsiders to identify the satellites for them. I try to help by carefully matching measured doppler curves with doppler curves that are calculated using the available TLEs. Usually my ID information is used in CelesTrak's SatCat. But the 18thSDS applies the strict rule that they may only accept ID information coming from the Owner/Operator of the involved satellite. Unfortunately many satellite owners don't know that they are responsible for identifying their satellite and then inform the 18thSDS accordingly. Also many foreign entities don't (want to) inform the 18thSDS of their satellite IDs. Therefore you see many unidentified objects in the SatCat, even though IDs are available through other sources.
'Satellite names' is another long discussion...
73, Nico PA0DLO
On 13-12-2024 21:47, David Spoelstra via AMSAT-BB wrote:
I’m trying to understand the process of naming satellites and putting their TLEs in the official sources.
It seems like Space-Track is the official source of TLEs. Is that correct? It seems like CelesTrak and AMSAT are secondary sources. Is that correct?
It seems like the process is this:
When a satellite is first launched, various people associated with it post preliminary TLEs with a temporary ID number. 2.
At some point an official ID number is generated. Who does this? I’m assuming NORAD? 3.
At some point, the satellite is given a name like “AO-123” versus “2024-199AY” or “OBJECT AY”. Who does this? Is that an “official” name that all TLEs should use? 4.
At some point it seems like the TLE sources align with the same name. Who drives that?
For example, let’s take AO-123. AMSAT lists it as:
AO-123
1 61781U 24199AY 24347.80600981 .00010127 00000-0 42052-3 0 9997
2 61781 97.3799 212.0032 0019112 106.8236 253.5099 15.23855779 49614
Space-Track lists it as:
0 OBJECT AY
1 61781U 24199AY 24348.46265841 .00010225 00000-0 42439-3 0 9990
2 61781 97.3798 212.6494 0019118 104.7477 255.5880 15.23869705 49716
CelesTrak lists it as:
2024-199AY
1 61781U 24199AY 24348.46265841 .00010225 00000+0 42439-3 0 9999
2 61781 97.3798 212.6494 0019118 104.7477 255.5880 15.23869705 49716
When will Space-Track and CelesTrak list it as AO-123? Who decides that?
Also, why is AMSAT’s TLEs so far behind Space-Track and CelesTrak? Notice AMSAT lists revolution 49614 versus the others that list revolution 49716 so it’s quite a bit behind.
Lastly, sometimes the TLE sources never seem to align on a name. A good example of this is AO-91. AMSAT lists it as:
AO-91
1 43017U 17073E 24347.62953177 .00010752 00000-0 59525-3 0 9997
2 43017 97.5481 217.2046 0193324 54.2789 307.6249 14.99383406382348
However, CelesTrak lists it as:
RADFXSAT (FOX-1B)
1 43017U 17073E 24347.89647055 .00011020 00000+0 60999-3 0 9996
2 43017 97.5480 217.4635 0193277 53.3813 308.5014 14.99389431382386
Why don’t they use the same name after all these years? Who decides that?
Thanks for helping me to understand the intricacies of this process.
-David, N9KT
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