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Amateur Astronomy – Watching the sky for the ISS

November 4, 2007

The next couple of weeks are the perfect time to seek out the International Space Station.

The ISS just got a bit bigger over the past week, as they have deployed a massive solar panel, and the space shuttle is currently docked. The extra solar panel makes the ISS brighter. Not that we need the ISS to be brighter in the night, it’s extremely bright and you just can’t miss it.

There is also a remote chance you will be able to see the Space Shuttle chasing behind the ISS, after it un-docks on Monday morning and prepares to come home.

It doesn’t matter where you are on the planet, from time to time, the ISS will pass by. The visit is usually only 3 or 4 minutes until it’s gone from one side of the sky to the other. Usually, from Newmarket, Ontario, Canada, ideal conditions exist at least once per week, sometimes more.

Isn’t it wonderful to see something with the naked eye? You don’t need a telescope, all you need is a sense of direction and time.

ISS Space Station Pass Back of House

What you’ll need to accurately find the ISS as it passes by:

  1. A compass. Any old compass will do.
  2. An inclinometer. What’s that? It’s quite simply a tool to tell you how high up you’re looking in the sky. Here’s a link on how to make a Home Made Inclinometer for $0.00.
  3. An accurate watch. You will need the seconds to be as accurate as possible. Syncronise a wristwatch to just about any computer that’s on the web, or go to the National Research Council of Canada for the official time.
  4. A “prediction” web site that will tell you when the ISS is going to pass over. I use Heaven’s Above. Although we call the task of calculating when the ISS will be visible a “prediction”, the truth is that it is accurate. Deadly accurate.

For the Greater Toronto Area, the predicted passes are every morning this week and next!

Some passes are better than others.

Not all predicted passes have a preferable magnitude (brightness). This can be for many factors:

  • Day or Night pass
  • Angle of the Sun
  • Angle and phase of the Moon
  • Most of all, because if the ISS does not pass directly overhead, it can be thousands of kilometers away, which means that it will cross the sky low to the horizon. Lower to the horizon means that you look through way more dirty atmosphere – and to be quite honest… it’s just not as exciting.

The best time to view the ISS, is when it passes at night and almost directly overhead. Unfortunately, the ISS will not be swinging around during the night, and all predictions for the week ahead have it passing just before sunrise. This is OK, and should make for an interesting start to most people’s commute.

Here’s a breakdown of the predictions of magnitude (brightness) for the week ahead:

Date, Magnitude, Start time.
5-Nov 0.4 5:52:32
6-Nov -1.8 6:14:35
7-Nov 0.2 5:04:32
8-Nov -1.9 5:27:17
9-Nov -2.1 5:49:47
10-Nov 0.8 4:40:42
10-Nov -1.1 6:12:05
11-Nov -0.1 5:02:52
11-Nov -0.5 6:34:38
12-Nov -0.6 5:24:55
13-Nov -0.5 5:46:53

Given that the lower number magnitude (and even better if it’s a negative number) are the best brightness for viewing, we will narrow down our choices to the better ones.

Date, Magnitude, Start Time, Altitude, Direction, Max Brightness Time, Altitude, Direction, End Time, Altitude, Direction

6-Nov -1.8 6:14:35 10 SW 6:17:23 59 SSE 6:20:16 10 ENE
7-Nov 0.2 5:04:32 17 SSE 5:05:22 19 SE 5:07:33 10 E
8-Nov -1.9 5:27:17 40 SSW 5:28:01 57 SE 5:30:51 10 ENE
9-Nov -2.1 5:49:47 31 W 5:50:49 51 NNW 5:53:39 10 NE
10-Nov 0.8 4:40:42 15 ENE 4:40:42 15 ENE 4:41:21 10 ENE
10-Nov -1.1 6:12:05 16 WNW 6:13:45 26 NNW 6:16:17 10 NE

I have included a little more data on the above chart. As you can see, there are 3 distinct phases of an ISS pass

  • Beginninig – this phase is where we hunt. Grab your compass and inclinometer, and stake out a spot in the sky to begin scanning. As the time for the initial visibility comes closer, you may think you’re seeing an airplane, far away… it’s moving slow, REAL slow, but then, it starts to speed up. Then it *REALLY* starts to speed up. It’s moving to the your next milestone in the sky – the Maximum Height. It will be there only another 45 or 60 seconds, so don’t be thinking you can dart inside for a camera.
  • Maximum Height – at this stage, it’s really rockin. It’s moving SO fast, you can’t believe it. It’s at this point that the ISS has reached it’s maximum brightness. If you’ve chosen a night where the maximum altitude is around 90 degrees, then your neck should be craned almost directly up.
  • Fade away – the ISS will appear to slow down now, and get dimmer as it moves across the sky. It will slow down to almost the rate you saw it appear. Sometimes, the ISS doesn’t just disappear below the horizon, sometimes it disappears in the middle of the sky! The reason for this has to do with the earth’s shadow. Expect this kind of a dissappearing act about 50% of the time.

Time to Choose a night.

I choose:

9-Nov -2.1 5:49:47 31 W 5:50:49 51 NNW 5:53:39 10 NE

for the following reasons:

  • Time in the morning is ok – I can get up early to watch it. (what a way to start a day!)
  • It will start to appear at 31 degrees up. This means I can see it above my neighbors’ houses
  • The whole shebang will last for almost 4 minutes
  • The maximum height is 51 degrees up, very high.

Pass Details


Friday, 09 November, 2007



Observer’s Location:

Newmarket ( 44.0500°N, 79.4500°W)

Local Time:

Eastern Standard Time (GMT – 5:00)


340 x 344 km, 51.6° (Epoch 02 Nov)

Sun altitude at time of
maximum pass altitude:


Using the predictions web site, let’s click on the November 9th event and find out more specific details.

By selecting November 9th, we are able to get more accurate information about this pass. Importantly, we can have a better idea of direction, and an idea of the distance in kilometers between me and the ISS. (It’s suprisingly less kilometers than you might think!)

Event , Time, Altitude, Azimuth, Distance (km)
Leaves shadow 5:49:47 31° 274° (W ) 627
Maximum altitude 5:50:54 50° 340° (NNW) 442
Drops below 10° altitude 5:53:39 10° 51° (NE ) 1,297
Sets 5:55:41 0° 57° (ENE) 2,135

Wow! At 5:50 and 54 seconds, the ISS will only be 442 km. away from my eyeball! It’s going to look so close, you WILL want to reach out to it with your hand. I promise!

Some final advice.

BE PUNCTUAL! The ISS waits for no one. Most events, from start to finish, last only 4 minutes at the longest. Imagine the ISS crossing the entire sky in 4 minutes. When the predictions web site says 5:49:47AM, it really does mean 47 seconds!

Line up and identify the 3 positions ahead of time. This will allow you to visualise how the ISS will move across the sky, and will help you identify the best viewing location. (ie. Front yard, backyard)

Photography. Take some pictures of the sky (without flash) in advace. This will give you the opportunity to play with some settings. If you have a simple digital point-and-shoot camera, switch it into the “Shutter Speed Priority” mode, and start off with about a 5 second shutter speed. A tripod or sturdy angled base is very necessary for this amount of shutter time. You will end up with a streak, so it helps to visualise the path of the ISS ahead of time, and position your camera to the known point in the sky where it will cross.

Be excited and pass it on!

Just imagine how those first viewers felt looking at Sputnik for the first time. What a world we live in.

Here’s some pictures I recently took.

ISS Longer Trail toward Houses IMG_2371

ISS Trail over Tree IMG_2368

4 Comments leave one →
  1. November 5, 2007 11:55 am

    This is great advice for folks wanting to see the ISS. One thing to add for folks wanting to take a picture – focus ahead of time on the moon or stars or something extremely distant. This morning, I tried to get the Moon, Venus and the ISS in the same frame (they were all within 6 degrees of each other) and misadjusted my focus. I got the shot, but it’s out of focus. Ah well…

  2. realworldnumbers permalink*
    November 5, 2007 9:54 pm

    Ed, that is an awesome tip! Even though it’s out of focus, i’d still love to check out the pics. Why not send me a copy at … I wonder what part of the world do you live in.

  3. November 6, 2007 3:35 am

    Great post, thanks for the link!

  4. July 12, 2011 10:46 pm

    Is there a way to find past data? I was camping and everyone insisted it was the ISS. I thought it was too bright myself; it was the brightest object of that size I’ve ever seen in the sky in my life (not counting meteors). Lemme know! (Clintjcl at

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