Extending Your Satellite Catalog
Both of these programs are good programs but there are a number of fun things you can do with them that are not obvious.
The database of satellites that it uses comes from a site - CelesTrak. That is the only site that you can have your TLEs updated from - automatically. That site gets their TLEs from the satellite catalog provided by the Combined Space Operations Center (the CSpOC, it was the Joint SpOC until recently) which is an organization of the United States Air Force.
The CSpOC puts satellites into lists and sites like CelesTrak just copies those lists (like weather satellites) and provides them. Some older satellites are regarded as not interesting enough and so are not in any list. If you want to track them (there are very good reasons for doing that) you have to go to Space-Track.org and copy the TLE yourself and manually load it into your software.
Another thing a Gpredict user might do is get a list of satellites that are available from the astronomer community and put those into your list of satellites. All of the "off the books" satellites - both satellites with guessed catalog number and with satellite numbers of 9x,xxx - that I am interested in I get from the astronomer list. It is also pretty easy to get this list of astronomer TLEs into JSatTrak. It is also possible to get orbital information from the International Scientific Optical Network, a group of observers that hosts orbital information on a computer in Russia. More details about that to follow.
An early stop should be to the Visual Satellite Observer’s page and within that is a page of resources http://satobs.org/tletools.html - this site is linked from that page so you probably arrived here from there. Copy the "classified" list of TLEs (this list is not actually classified, that is just the name) and unzip it. It is just a text file - change the extension (we are all using Macs here??) from .tle to .txt and open it with TextEdit or something.
Once you have the astronomer list, you can generate ground traces for satellites that are NOT available from CSpOC/CelesTrak. Here is another example, one that has a "shark fin" ground trace. The ground trace also tells us that this object was launched from Cape Canaveral since that is as far north and south of the Equator that it gets.
Especially if you are interested in CubeSats and similar small satellites, there are a few sources of TLEs for satellites where the CSpOC does not release them. Send me email and I will elaborate.
Getting the astronomer list into Gpredict:
1. Create a folder “For Gpredict” on your Desktop.
2. Put the file of TLEs you got from the Visual Satellite Observer page into that folder, open it with TextEdit, select the entire file and clear formatting just to make sure that you don't have any invisible characters in the file - you must have a file that is just plain text. At this point you can also edit the names of the satellites. Some people go on about invisible check sums - that is not a real problem. Name the file weather.txt so that it has a name that Gpredict is looking for. I had trouble if the TLE is not in EXACTLY the correct columns - that will cause Gpredict to not find the TLE and there is no alert.
3. Go to the Edit menu and tell the system to update your TLEs from “Local Files”
4. Navigate to the "For Gpredict" folder and select it. Note that you CANNOT select the file of TLEs, you must select the folder!
If you have a bit of skill with Unix, you can also edit the name of satellites in Gpredict. This way you can produce ground traces from satellites that have not yet been launched, etc. I will add those steps in the near future. But it is easier to edit them (as I earlier) before you add them to your data.
JSatTrak
Adding other TLEs is simple in JSatTrak - as I mentioned on the JSatTrak pages. Just go into the "data" and under that the "tle' folder in the application and paste the TLE into one of the lists of satellites that you see there. In JSatTrak the TLEs are just text files and can easily be found and edited.
A "Gotcha"
If you have edited the names of any of the satellites, when you update your TLEs it will overwrite your changes (if that TLE is updated). So remember what you did and go back and do it again.
