EOSOP Tutorial

EOSOP Observing Program – Tutorial


Before you go searching for the “back” button on your browser, please bear with us. This tutorial is NOT a mathematically intensive analysis of orbit determination, but rather a basic summary of the concepts that will give meaning to the observing lists shown above.

The observing tasks for the EOSOP award are listed below.

  • Active Payloads – Observe four (4) different active payloads, e.g. weather satellites, communications satellites, scientific payloads, etc. that are currently operational. Examples include the Hubble Space Telescope.
  • Manned Spaceflight – Observe three (3) manned spacecraft. These must be spacecraft that are occupied by humans at the time of observation, and might include the International Space Station, Soyuz spacecraft, a Chinese manned spacecraft or the newer SpaceX dragon or Boeing Starliner spacecraft.
  • Multinational Satellites – Observe satellites from five (5) different countries (other than the USA). These spacecraft must be owned by the country noted, but don’t have to have been launched by the country that owns the spacecraft.  USA, Russia and the European Space Agency regularly launch payloads for other countries.
  • Rocket Bodies – Observe four (4) rocket bodies. These are usually noted by “R/B” in the satellite name in the element set.
  • Multi-pass – Observe two (2) satellites on two separate passes, each pair of passes must be observed in a single night.
  • Formation – Observe two (2) sets of formation flights. These will usually be a Soyuz or resupply spacecraft flying in formation with the ISS just before or after docking. The two spacecraft should be on the same orbital path, and separated by no more than 30-40 degrees. There are also GRACE and Terra/Tandem SAR-X pairs – contact the Coordinator for more information.
  • Aged Element Sets – Observe two (2) satellites with element sets of different ages. For each satellite, one observation must be with an element set less than one week old, and the second observation must be with an element set at least three weeks old. The purpose is to see the effects of using old element sets, and their effect on the arrival time of the satellite. Taking accurate observation times is especially important in this task.
  • Constellation (2) – Observe two different objects in the same constellation of satellites. A satellite constellation is a group of artificial satellites working together as a system to provide greater earth coverage then any single satellite. They are found in all orbit regimes; however, the constellations easiest to observe for this requirement are found in the low earth orbit. Typical constellations are the Starlink, A-train, SPOT and others.


1. A single pass of a satellite can only be used to satisfy a single task. i.e., a single observation of a Spot satellite can be counted as an active payload or a foreign satellite (France), but only one.
2. Another issue that has caused many observers to repeat observations has been the submission of an observation which cannot be verified. To avoid this problem, include information in your sibmission that includes the source of your element sets.  This will enable the Coordinator to verify your observations

Collecting Observations:

We’ve attempted to make the process of collecting observations as easy and direct as possible. The first thing to do is to download the observation report form (in Adobe PDF or Microsoft Word format), and print off one per observing task, 28 in total. If you have Microsoft Excel, you might also choose to download the EOSOP Observation Checklist. We’ll discuss the observation checklist later. The observation reporting forms must be completed by each participant, and submitted in order to get credit for each observation. Please note: make copies of your logs, we are not able to return logs submitted for EOSOP credit.

There are a number of fields that must be completed on each observation report form. Some are obvious, like name and date of observation, but others deserve additional clarification. The process of verifying observations is time consuming, and we require this information to make our verification process as quick as possible.

  • Observers Name – Please enter your name here, as you would like it to appear on your certificate.
  • Date of Observation – Specify the date of the observation, INCLUDING the timezone in effect at the time (EDT, PST, etc.). You are also welcome to use Greenwich or UTC if you like. When you include your time hacks on the sketch, please use the same timezone noted in this field.
  • Satellite Name and ID – Enter the common name of the satellite AND the satellite id (either the catalog number appearing in the first field of line 1 of the element set, or the XXXX designator appearing in the second field of line 1 of the element set). For example, “Cosmos 2533 R/B, 25063U”.
  • Date of Element Set Used – Enter the date of the element set file used for this object. You can include either the date of the element set file, or optionally the date the file was downloaded. Do not include the complete element set itself, as this is a violation of the user agreement that is in place with the originator of the data (NORAD, etc.)
  • Location of Observer – Enter your observing location. Be sure to use decimal degrees, and not degrees/minutes/seconds.
  • Instrument Used – Please check the appropriate item.
  • Comments – Include any comments that would clarify the observation, for example, the satellite brightness, whether it was flashing, if it faded out, satellite was X seconds late, etc.
  • Observation Number – This field is especially important if you choose to use the optional Excel observation checklist. Please assign a number from 1 to 28, corresponding to the objective on the checklist. If you don’t use the Excel checklist, this field is optional.
  • Sketch of Observation – You must include a full sky sketch of the satellite pass. Please include the following items in you sketch:
    1. A solid line showing the path of the satellite across the sky (use a dashed/dotted line for flashing satellites)
    2. At least two time “hacks” indicating where the satellite was in the sky at those times. As mentioned earlier, the time written on the sketch should be in the timezone noted in the “Date of Observation” field above.
    3. One or two reference constellations to indicate the path of the satellite with respect to the background stars.
  • Observation Objective – Check which item in the program list is being satisfied by the observation recorded on each form. Note: Each form should contain only one satellite passage, except the formation flights, which should have both satellites on the same observation reporting form.

Observation Checklist:

An optional observation checklist is provided for your convenience. This file, in Microsoft Excel format, can be used to assist in keeping track of the observations you are collecting. It has a number of formulas and logical checks in place to help prevent duplicate observations, or allocating a single observation to more than one observing task, etc. To use this spreadsheet, simply enter the target information in the observation table at the top (table 1), and transfer the observation number to the task table at the bottom (table 2). The built-in logic will identify any duplication problems, and will notify you when all tasks are complete. If you use this checklist, please include a printout of the completed checklist with your observations logs when you submit for your award.

Propagation Software:

There are a wide range of planetarium programs and specialized satellite tracking programs available to those interested in tracking satellites, some of which are listed on the EOSOP Resources page.


To go bck to the EOSOP Observing Program main page, click here.

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