Regarding TLEs:
We are working on a preliminary TLE from the state vector provided from the launch provider and will upload that here once we have it finalized.
We have found in the past that the TLE’s you all generate are better than those provided by the launch providers (e.g. those calculated for CUTE by @EelkeVisser with help from @cgbsat , I believe). We have some students working on learning how to do our own TLE calculations, but I was wondering if anyone from this forum was interested enough in this launch to work on updated TLE’s for CTIM in the first few days of launch.
To estimate a TLE before launch, all we really need are the expected perigee and apogee altitudes and the orbital inclination that this launch is targeting. If perigee and apogee don’t differ too much, then the location of perigee is not important, and we can assume a circular orbit to start with. The other parameters of the orbits are then essentially set by the launch time and the launch location. For the purposes of tracking the first few orbits with the SatNOGS ground stations that would be sufficient.
Fitting a 500 km 45 degrees inclined orbit through this point for a drop/launch at 2022-06-30T06:00:00 (with 5 minutes offset for acceleration) gives the following orbit:
Be careful with this TLE, as it is nothing more then a wild guess. It certainly does not have the accuracy we are used to, and can be quite off!!! Also, i would like to invite anyone to check it for mistakes. And if the launch gets delayed, the TLE needs to be updated too.
This looks like a drop during darkness. I think this is weird. I would assume it is easier to launch in daylight, to allow easier filming of the launch:
Hey folks! The TLE our student calculated from the state vector provided from our launch provider is below. This uses an updated approximate drop time of 2250 pacific time. Unfortunately we aren’t allowed to provide access to the state vectors:
I notice it looks different from that calculated by @EelkeVisser . I will be sure to take note at what time the drop/launch really happens and post it here.
Your CTIM TLE does not match the launch trajectory, but I may have made a mistake converting the 22:50 PDT time to UTC. I believe that should be 05:50UTC on June 30th. If I move the time by 2 hours to 07:50UTC then the orbital plane matches, but CTIM is running too early in its orbit.
Hey @cgbsat , it’s possible the difference you are seeing is that our student used the deployment time (2022-06-30T06:45:28.849 UTC) rather than the “drop time” (I think this refers to when the rocket will disconnect from the airplane, of 22:50 PDT). This came from a conversation with the launch provider
Regardless, they found an issue with their STK model and came up with the following TLE:
The difference is around to two minutes, so whatever we use on Network will work. Due to the nature of the launch I’ll wait till the drop/launch for adding them as any change in the drop/launch time means new TLE set. We will have plenty of time until deployment to schedule observations. @afyhrie Do we expect CTIM to start transmitting right after the deployment or there is a radio silence period?
EDIT:
Here is the difference visualized over one of its pass over Europe (CTIM-3 @afyhrie TLE set and CTIM-550 @EelkeVisser TLE set):
@afyhrie feel free you or anyone from your team, if you haven’t already, to join the #satnogs matrix channel for more live updates and discussions on the launch, the TLE sets etc…
Just a heads up that the TLE shared by @afyhrie is a better match to the reported rocket stage drop zones, so I would suggest to use that as your primary TLE. Fingers crossed for a smooth ride to orbit!
It looks like the stream isn’t online. @afyhrie if you have access to the private video, let us know the exact drop/launch time in order to adjust the TLE set.
Hey folks, like @fredy said the launch was postponed due to some temperature issues. From the vendor: "The decision has been made to recycle back to L-1 tomorrow (6/30) so the next available launch attempt will be Friday 7/1 between 2200PT-0200PT. "
Once I have more detailed drop/deployment times I’ll share them as I am able! Then the TLE re-calculation can begin, if you want. I’ll also share the preliminary TLE’s that our team comes up with.
The team will be attempting another launch this evening, 7/1.
Updates to the Drop Time have been made, but we only have a preliminary schedule and will receive an updated schedule in a few hours:
Takeoff: 2240 Pacific
Drop: 2345 Pacific (this is not deployment, I think, but when the rocket will detach from the airplane)
Network has 177 observations scheduled for the first 10h. To station owners, if you want to schedule have in mind that the TLE set is preliminary and not accurate, so don’t schedule too far in the future.
EDIT: after re-watching stream and discussing with @EelkeVisser in our matrix channel, the launch time was at 06:53:05 UTC. However 15s will not make significant difference for the TLE, so we keep the ones above.
(better than none :P):
