JPL-SATS

Introduction

There are several old rocket stages and scientific missions beyond the low Earth orbit.

It's difficult to find out the actual position in the sky, mainly because there is, for satellites near Earth, a substantial geometric offset from an Earth-centered based ephemeride.

The JPL Horizont website allows the user to do this for almost all artificial satellites (and other small solar system bodies). But the website user interface is very time-consuming, and the output is very unusual with long numbers and difficult to read.

Use

You must know how to use the command line. You should know WGET, but you can also download the binary (see below).

My program downloads the ephemerides of a satellite from the above site and changes the output to the well-known MPC format output for the next 14 days from the time of starting this program.

You must know the 3-letter MPC code for your observatory or an observatory nearby. You can download this list from MPC: https://www.minorplanetcenter.net/iau/lists/ObsCodesF.html. You need the first column with the 3-letter Code. If you want a quick search, you may use also this Map. Wikipedia has a list with clickable maps for the codes.

Additionally, you must know the satellite ID. otherwise, the program would create a full run of all satellites. This complete run is not documented, so it's only useful for advanced users (see below). This satellite ID you can get from https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND='MB'. It's the ID in the first column. The id starts mostly with a minus sign for an artificial satellite.

Then you start at the command line the program with jpl-sats Code ID. If you only use jpl-sats you get syntax information. An example is jpl-sats C95 -170. This calculates the ephemerides of the JWST (James Webb Space Telescope) for the C95 station in the next 14 days. After each run, the ephemeride is presented in your standard browser.

Now you can use the ephemeris in your tools and programs. If you need other formats, please contact me.

Advanced use

If you give only a station code and no satellite ID, the program will check all satellites available at JPL. This will need some time.

At first, the program downloads the list of all satellites. In the first run, it checks, which satellites are too far away. All satellites at a distance of more than 0.1 AU are ignored. Satellites that will start in the next 14 days will be listed in the file future.html (also available on this site). Satellites with ending ephemerides in the last 14 days will be listed in the file last.html. In the second run, all visible satellites will be calculated and saved into sat-name.html files and a complete ephemeris.html file. The index is given in eph-index.html.

If you want you can download the file ignore.txt and add this to the root of jps-sats.exe. All satellites in this file will be ignored (e.g. too near the moon or Earth etc.). jpl.mags contain H(0) magnitude to predict the magnitude better for bigger satellites. This would ignore also a single satellite given with the ID! See format examples.

Here are sample ephemerides for my station C95.

Downloads

You must download the following two programs:

• JPL-SATS.EXE from this website. Because it's a self-written program, Windows may warn you that this is an unusual program. Also, some virus scanners may tell you, it contains a virus. It doesn't. If you are anxious, you can try it on a virtual operating system.
• WGET binary from this website. But maybe you have it already. Try WGET at the command line, then you don't need this download. But WGET must be not too old. Otherwise, download this binary.

If you like this tool, please be so nice to give me a donation. Thank you.