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International Space Station Sightings
Managed By: Icon Here Space Science
This is game that requires two or more players to "catch" the International Space Station as it passes across hundreds of miles in one of its orbits around the globe.
Expanded Description:

This relatively simple challenge is to observe the International Space Station (ISS) one minute before or after at least one other player sees it from their location. Participants need to be at least one minute of ISS travel time (293 miles or 472 km) apart, and the ISS must reach at least 45° altitude for all players located below 55° N/S latitude* All players will have to spot the ISS during the same orbit. All pertinent information about the ISS is available at Once a team is set up, if only one member sees the pass because the other player or players were clouded out, the one that did make the observation will still get credit if that participant states why the other participant/s didn’t see the Station. Please also state the other player’s name/s and approximate location/s. NOTE! Once a player gets an ISS waymark they can help another player to get a waymark of their own. The ISS waymark owner will simply need to (virtually) “**visit” the other person’s new waymark once it’s created. For more info about visitations see the “visitation rules” near the end of this text.

To find a partner you'll need to use Heavens-Above to get ground track information. In that way you can see where the ISS is going. The ground track indicates all points along which the ISS will be seen to fly directly overhead. You will use those ground coordinates to locate a list of distant geocaches (or waymarks) and cache (and waymark) owners that might want to participate.

Theoretically three players could see the ISS pass over one after the other across about 900 miles (1,448 km). If you attempt to set up a team of three for one pass, the ISS will probably start in bright twilight for the most westerly player and move into the Earth’s shadow before it crosses the whole sky for the most easterly participant. The band of daylight that the ISS flies through over areas that are dark enough to see it is pretty narrow most of the time.

Still not sure how to play? Detailed instructions, in brown font, after the double line "============" below will take you step-by-step through the process. Helpful hints have been posted here at the Iowa Geocachers website.

This challenge will require planning ahead since the ISS does not often fly real high over any one area. Be prepared, clouds (or even a forgetful mind) may spoil even the best well planned attempt. For that reason you may want to plan on observing more than one event with other players.

Once you claim an ISS waymark, you can help a different player and get credit for a **“visit” to theirs. I myself would like to shoot for a maximum distance record. Would any schools be game?

What You Need To Do To Get Credit For Making A Waymark In This Category, Including The Data That Needs To Be Shared Between Members Of The Group.

(1) Each participant

*will have to see the ISS moving 45° or higher in their sky one after or before the other. [Note: to locate the altitude of passes over my area I began at this Heavens-Above main page for my town. I then clicked on ISS and found a good pass here on 22 October, 2006. I clicked on the blue date and came to this pass details page from which I get to the ground track.]

(2) Here is the info you need for naming your waymark.

A list of the cities nearest to each observation site in the order that the pass occurred. Make sure to include your “site number” (like site-2) in the sequence.

For example….

Pierre, SD – Waterloo, IA – Nashville, TN- site 2

(3) Here is what you need for the short description.

A list of the nicknames of each of the players involved in the order of their sites.

For example….

Coyotes, Lycan and Country Singer sighted the ISS during one pass on January 3, 2007.

(4) Here is what you need for the long description.

For EACH site you will need to list the following information (1) The time of maximum altitude. (2) The maximum altitude. (3) The predicted magnitude. (4) The distances covered by the ISS between each site consecutively plus the total distance covered. You will need each other’s coords and may need to use this facility or FizzyCalc to determine the distances. (5) The total time of travel between all sites. (6) The local sky conditions. (7) Your story, e.g. what you experienced and learned etc. (8) I would like to see a picture similar to this one showing your GPSr reading the location where your observation was made. A picture of the ISS moving by is not required but would be great to see! If do not own a camera feel free to write to Iowa Tom to see if he will make arrangements for you to get credit anyway.

For example….

At 16:51:32 MST the ISS reached at an altitude of 82° and a magnitude of -1 over Pierre, SD. At 17:53:04 CST it reached an altitude of 67° and a magnitude of -0.6 over Waterloo, IA. At 17:54:59 CST it reached an altitude of 62° and a magnitude of -1.0) over Nashville, TN.

Pierre is 423 miles from Waterloo. Waterloo is 528 miles from Nashville. The total distance covered was 911 miles.

The time the ISS took to travel the whole distance was 1 min 27 sec.

The sky in Pierre was clear. The sky in Waterloo was partly cloudy. The sky in Nashville was slightly hazy.

About the ground track, and finding distant good places to be at: the dotted part of a ground track indicates that the ISS directly over that area will be in shadow. Hence, don’t go to that part of the line when looking for a high pass! I find it easiest to go toward the sunset (or sunrise for a morning pass). The problem with that is you may find that the same pass is not listed a few hundred miles closer to twilight from your location. That would be because the other location has too bright of twilight for the pass to be visible. Also, local high passes always occur closer to local sunset or sunrise.

If at all possible it would be great to communicate by cell phone during a shared experience. I myself think it would be especially neat if each of you planned to make the observation at a place where you could each hide a cache, maybe just a micro. Dedicate the cache to your accomplishment! Maybe name it something that’s searchable as a group like this: "[your nickname] ISS Observation Cache." Here’s one that I made to promote this game. I also started a Space Shuttle TB to go along with it.


In case you need them here are the detailed step by step instructions as promised.

(1) Go to Heavens-Above and locate your town or a town close to where you want to make your observation. Doing it this way will automatically get the time zone correct. Otherwise if you wish, do it the more technical way by entering your coordinates and the time zone offset from Universal Time here.

(2) Once you arrive at the Heavens-Above home page, under Satellites click on the ISS link.

(3) Look for a pass that is at least 45° at its Max Altitude. You may have to click on the “Next” link a few times to find a suitable pass. All times are listed in military time. Once found, note the date and time and write it down, copy it, or save a shortcut to it. You’ll need that time and date info later.

(4) Once you find a good pass with a maximum altitude of at least 45 degrees above your horizon, in the details table click on the blue date. Make sure to save the link!

(5) Now click on the Ground Track link located in the upper left corner of the Visible Pass Details page. Save the link! [Not important for this challenge is the light colored area shown there. It indicates the area in which the ISS can pass and still be visible from your location. It’s a large area! If the astronauts were in the center of that, the perimeter would be the limit of how far out they could see. They can never see farther north or south than about 70°.]

(6) The coordinate lines shown on the ground track are in 10 degree increments. I’m in between 40° N and 50 ° N and 80° W and 90° W. Follow the ground track toward an area that shows a solid line and find a spot that is at least one minute ISS travel time away from you. For evening passes it’s usually better to look for someone west of you rather than east of you.

(7) From your study of the ground track estimate the coordinate for a good place for site 2. MAKE SURE TO GIVE ALL WEST LONGITUDES A “–” SIGN. Any place along the ground track will have a very high pass. It’s simpler to pick a latitude or longitude along the line, like 100° W then estimate the other coordinate between the lines, like 43° N.

(8) Once you choose a coordinate for site 2, go back to the “ISS - Visible Passes” page that you were at earlier.

(9) Once there, look at the URL displayed in the address bar along the top of your screen. Find the coordinate in the URL. I made it red in the following example of Cedar Falls: Edit the coordinate for the new site. If you like, edit the name of the new location too. Finally, if you know that the time zone for the new location is different, make sure to correct it! It’s listed at the end of the URL. For example, CST stands for Central Standard Time.

(10) Now click your keyboard Enter button. Is your new location close to the ground track? If it isn’t, make the necessary adjustments in the coord in the URL and try again. Once you get it right, click on the Heavens-Above icon on the upper left of the webpage. You will need to go to the “ISS - Visible Passes” info and find the same pass that you yourself hope to see. Not counting a change in time zones, it’ll probably be within four minutes of yours. Remember, the other person should also have a high pass! If your pass is not listed at the other location, then the one you chose is probably too close to the time of sunrise or sunset there. Save your final links.

(12) To find a person to collaborate with go to the Tools for Finding and Hiding Caches page and enter the coordinate you came up with.

(13) Find what looks to be a player that has more than one cache in the area and go to their profile. Do they look promising? If they do, use to go to a cache near the coordinate of site 2. If you suspect a change in time zone you will need to see if they will see the ISS pass an “hour earlier or later than you” by using the map facilities on the cache webpage to locate a city in the same time zone as where the cache is located. Assuming they live near that town go back to Heavens-Above and enter the name of the town there. If it’s listed look up the pass again and save the link! Note to see if the time zone (UTC offset) is different than for your place.

(14) Prepare an explanation about what you hope to accomplish by collaborating with them and drop them an e-mail with the URL of where they should be for the best possible pass. Include the links for both their pass and yours. If they agree to go for it, cross your fingers and hope for the best. Make sure they know the rules and good luck!


*Special rules for the far north and far south observers:

For any locations between 55° - 56° N/S latitude, the ISS only needs to make it to a maximum altitude of 30°, not 45°. All places closer to the equator need at least a 45° pass.

For any locations between 57° - 58° N/S latitude, the ISS only needs to make it to a maximum altitude of 25°.

For any locations between 59° - 60° N/S latitude, the ISS only needs to make it to a maximum altitude of 15°.

For any locations between 61° N/S latitude, the ISS only needs to make it to a maximum altitude of 10°.

Any location 62° or farther from the equator will not be able to participate.

**Visitation rules:

NOTE! The visitation rules are temporarily located at this webpage. They are the violet colored text.

Instructions for Posting a International Space Station Sightings Waymark:

Any waymark (sighting) in this "catch the ISS" category must have been a successful multiplayer sighting of the ISS as it passed above a certain required altitude in degrees above each person's horizon. Each player must have been at least 293 miles (472 km) apart.

Instructions for Visiting a Waymark in this Category:
The details of what to do are shown in green and just below the TO GET CREDIT heading in the detailed explanation above.
Category Settings:
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Image for ISS Sighting-Edmond, OK-Olathe,KS-Waterloo, IA-Ottawa, Canada-Brunete,Spain-Site2view gallery

EE33.6 km

Log it!

International Space Station SightingsISS Sighting-Edmond, OK-Olathe,KS-Waterloo, IA-Ottawa, Canada-Brunete,Spain-Site2

in International Space Station Sightings

Olathe, KS also had a break in the storms of 18May19 that allowed iconions to partner for the ISS waymark.

posted by: Groundspeak Premium Member iconions

location: Kansas

date approved: 5/22/2019

last visited: never

Premium Member Downloads: download.GPX Lite File       download.LOC File       download .KML File (Google Earth)