TLE data?

[pswiatki]

Please, excuse my lacking space knowledge (this is really new to me) - will TLE data set be known and published only after PWSat2 is inserted into its orbit (and then we can predict its visibility from any given point on the Earth's surface)?

[begreeen]

Basically you're right. However there will be ~70 satellites deployed one by one, so I will be hard to determine at very beginning which TLE is for PW-Sat2. We'll be trying and sharing our investigations :)

[pswiatki]

Right, I understand. So, you are saying you will be pointing the antenna at some point in the sky and trying to pick up the signal from PWSat2. All good, but I imagine you would have to have a rough estimate on Az/El angles for your first attempts, correct? Oh, or maybe this is the part where you look for support from the community (if your telemetry can tell you enough about the position of the sat) 👍
So - I imagine - as soon as frames start coming back to your server then it will become easier to tell the orbital parameters. Anyhow - I keep my fingers crossed that launch goes according to plans and PWSat2 will be operational when in orbit.

[begreeen]

We've got a rough estimate - derived from parameters of the launch place/time and destination orbit. Soon after the launch we should receive TLE of upper stage (not exactly stage, rather a deployer, so called free flyer).

During very first passes (estimated from TLE of the deployer) we'll use QFH antenna (omni-directional) just to figure out if our estimate is correct. Then we'll have a data from NORAD about 70 objects deployed from SSO-A and try to find the PW-Sat2. For sure community help will be very helpful, it's also the reason why we have a contest for the first received frame from the satellite :)

Unfortunately the launch is delayed to not earlier than Dec. 1st due to weather conditions... we have to wait a little bit longer...

[begreeen]

Passes above Poland would look like this:

(of course the dates are incorrect, but it's about hours, since for Sun synchronous orbit there are always passes around the same hour each day)

[pswiatki]

Thank you so much. This gives me the idea on how to prepare my equipment to receive the signal from PWSat2. All my tests will be done in southern Poland (either near Opole, Kraków, or Przemyśl ;) )

[zdanek]

@begreeen what software did you use to calc the passes?
regards, Bartek

[zdanek]

ok. I've found it: http://gpredict.oz9aec.net/

[pswiatki]

alright, but tell me (I have not checked / tried) - can the user enter only those orbital parameters that are known to them (say: preliminary, as is the case with PWSat2) and gpredict will calculate the passes over a given point on the surface of the Earth?

[zdanek]

@pswiatki I'm also interested because I only found this program. I didn't try to use it yet. Maybe @begreeen can tell us how to use it?
BTW @begreeen I've heard you today on the Radio. You told about difficulties of launching of the rocket. :D

[begreeen]

@pswiatki GPredict and similar software need TLE file. We use Systems Tool Kit (STK) and some manual corrections to obtain preliminary/predicted TLE. But it's better to wait for TLE from upper stage (available soon after launch).

@zdanek what do you want to do exactly with GPredict?

[zdanek]

@begreeen I want to use it for tracking PW-SAT2. Will GPredict see PW-SAT2 after launch?
Shall I add some TLE file from URLs?

[begreeen]

We'll publish a TLE file, you can add it using 'Update TLE from local files' or sth similar in GPredict.

[zdanek]

Where? I don't want to miss it. I have prepared UHF antenna and I'm looking forward receiving data from PW-SAT2.

[begreeen]

Over there: https://github.com/PW-Sat2/HAMRadio/wiki/Orbit-and-Tracking-(TLE)#tle-data
we'll publish important updates on Twitter too.

[pswiatki]

For some reason gpredict doesn't believe that preliminary TLE is valid and refuses to load it. Why is that? Should I tweak the data taken from your WIKI manually somehow?