<p>Geostationary satellites are often seen with telescopes and occasionally result in a
&quot;Something Moved! Did I see a UFO?&quot; sort of message.</p>
<p>If you have a tracking telescope aimed at a star in the same field if view of a geostationary satellite the satellite will appear to move against the background. It you turn off telescope tracking the satellite will appear to be stationary but the stars will move against the background.</p>
<p>Geostationary satellites come in various sizes shapes and reflectivity. No doubt the brighter satellites will be visible with binoculars.</p>
<p>Naked eye???</p>
<p>What a wonderful project for an aspiring astronomer. Sharpen up your Google, I will watch for your report.</p>

CC BY-SA 4.0
2020-08-31T19:56:59.473Z
2020-08-31T19:56:59.473Z
L d Bonnie
<ul>
<li><p>Have a look at <a href="https://space.stackexchange.com/q/33891/12102">Is it possible to capture geostationary satellites with DSLR?</a></p>
</li>
<li><p>See the excellent advice in <a href="https://space.stackexchange.com/a/12409/12102">this answer</a> to <em>Are any geosynchronous satellites visible with the naked eye?</em></p>
</li>
</ul>
<blockquote>
<p>No, but they are easily seen with a small telescope on a sturdy mount. March and September are the best times. Use an app to help you. <strong>My favorite way is to keep M11, the Wild Duck Cluster, in view with a medium power eyepiece. Every few minutes, a &quot;star&quot; will slowly track through the southern edge!</strong></p>
</blockquote>
<p>It's a <strong>fun and instructive exercise</strong> to calculate the declination of an equatorial GEO orbit from a given latitude!</p>
<ul>
<li>GEO satellites can be quite large, and while they are said to be +10 to +14 magnitude they can flare far brighter due to flat surfaces, both solar panels and thermal radiators. From <a href="http://www.satobs.org/geosats.html" rel="nofollow noreferrer">http://www.satobs.org/geosats.html</a></li>
</ul>
<blockquote>
<p><strong>Typically the satellite will be in the mag. +11 to +14 range (or dimmer), but brightening by several magnitudes when the geometry is favourable (around mag. +5 to +6 is not untypical). One satellite is reported to have briefly been visible to the naked eye at mag. +3!</strong></p>
</blockquote>
<ul>
<li>See Richard Huziak's (Saskatoon Centre (contact info in link) excellent tutorial <a href="http://adsabs.harvard.edu/full/2000JRASC..94...14H" rel="nofollow noreferrer">Observing Geostationary Satellites</a> reprinted from Saskatoon Skies:</li>
</ul>
<blockquote>
<p>...<strong>I found three other satellites, all between magnitudes 13 and 13.5, each a degree or two from the last!</strong> Chances are that one of the satellites is Canada’s Anik C1, although I could not identify it for certain.</p>
</blockquote>
<p>From Sky and Telescope's <a href="https://skyandtelescope.org/observing/how-to-see-and-photograph-geosynchronous-satellites/" rel="nofollow noreferrer">How to See and Photograph Geosynchronous Satellites</a></p>
<blockquote>
<p><strong>Many geosynchronous satellites shine between magnitudes 10–12</strong>, so you can spot them in telescopes as small as 4 inches. They're also easy to photograph. High ISOs and fast, low light lenses aren't necessary, just a camera capable of a several-minute-long time exposure — long enough for the stars to trail, so you can easily tell them apart from the satellites. Set your shutter speed to &quot;B&quot; and ISO at 400. You can hold the shutter button down with your finger, but a shutter release cable is much better and vibration-free. Use a 100–200-mm telephoto lens, focus sharply, and expose for 2–4 minutes. When you enlarge the image, you'll should see long trails and a line of pinpoint dots — satellites!</p>
</blockquote>
<ul>
<li><strong>See and enjoy the videos of</strong> <em><strong>GEO satellites colliding with space junk</strong></em> linked in <a href="https://space.stackexchange.com/q/27436/12102">Are commercial communications satellites in GEO being constantly monitored by telescopes?</a></li>
<li>From <a href="https://space.stackexchange.com/a/37454/12102">this answer</a> to <em>Are there any satellites in geosynchronous but not geostationary orbits?</em> we can see that while many objects in GEO have a well station-kept equatorial orbit, some are allowed a small inclination and others can have quite a large one!</li>
</ul>
<p><a href="https://i.sstatic.net/SwR8L.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/SwR8L.png" alt="synodic plot of GEO orbits" /></a></p>
<ul>
<li><p>Large communications satellites can have large flat surfaces that can dramatically increase their visibility at certain oriatiantations. These include solar panels that are often articulated to always point at the Sun, and large thermal radiators that have high thermal emissivity (are dark) in thermal IR yet highly reflective (mirror-like) in visible to avoid solar heating. For more on that see answers to <a href="https://space.stackexchange.com/q/21524/12102">What are these very large, square panels on Inmarsat 5?</a> and <a href="https://space.stackexchange.com/q/26544/12102">What is the function of this array of what looks like mirrors on TESS?</a> and some cool photos of spacecraft in question.</p>
</li>
<li><p>For some math, see answers to <a href="https://space.stackexchange.com/q/19382/12102">At what magnitude would adjacent large geostationary communications satellites see each other?</a> and <a href="https://astronomy.stackexchange.com/q/29957/7982">When would we detect a tiny meter size natural satellite in a geostationary orbits?</a>  and <a href="https://astronomy.stackexchange.com/q/28744/7982">Calculating the apparent magnitude of a satellite</a></p>
</li>
<li><p>For a truly weird looking communications satellite bound for GEO see <a href="https://space.stackexchange.com/q/37957/12102">Why do these satellite antennas look so weird? (strangely shaped with little white dots…)</a></p>
</li>
</ul>
<p><a href="https://i.sstatic.net/7GEH1.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/7GEH1.jpg" alt="Shiny surfaces on communications satellite" /></a></p>
<p><a href="https://i.sstatic.net/n5yTM.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/n5yTM.jpg" alt="Shiny surfaces on communications satellite" /></a></p>
<p>From <a href="https://space.stackexchange.com/q/20861/12102">How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints?</a> you can see thermal radiators that are highly reflective in the visible (and near IR)</p>
<p><a href="https://i.sstatic.net/DYQT2.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DYQT2.jpg" alt="Shiny surfaces on communications satellite" /></a></p>
<p>From <a href="https://space.stackexchange.com/q/19064/12102">How will GOES-R simultaneously point some instruments down at Earth and others sunward?</a></p>
<p><a href="https://i.sstatic.net/4gc8C.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/4gc8C.jpg" alt="Shiny surfaces on communications satellite" /></a></p>

CC BY-SA 4.0
2020-09-01T08:16:36.300Z
not exactly related, but don't forget radio observations! [“Mysterious radio signals” - how could a geostationary satellite and Ross-128 line up with Arecibo?](https://astronomy.stackexchange.com/q/21753/7982)
uhoh
CC BY-SA 4.0
2020-09-01T08:28:53.263Z
Brighter than I expected. But then I guess, 100 times further away and 10 magnitudes fainter than low-Earth orbit satellites is about right.
ProfRob
CC BY-SA 4.0
2020-09-01T08:43:20.157Z
@RobJeffries This was (obviously) fun to write ;-) if you (or anyone else) happens to spot one and can estimate a brightness, that would make for an interesting supplemental answer!
uhoh
CC BY-SA 4.0
2020-09-01T16:25:05.440Z
The October 2020 Sky & Telescope magazine has an article about observing them. Since they flare when the apparent declination of the satellite equals the Sun's declination, the flare "season" occurs near the March and September equinox. It has been years since I saw one, and it was through a car windshield, but I think they can easily reach second magnitude under the right conditions (date, time, and satellite design.)
JohnHoltz
CC BY-SA 4.0
2020-09-01T16:45:45.113Z
@JohnHoltz Thanks! Consider adding another answer summarizing what's in that article, or please feel free to edit this answer.
uhoh
CC BY-SA 4.0
2020-09-01T08:01:00.760Z
2020-09-01T08:18:34.760Z
2020-09-01T08:18:34.760Z
uhoh
<p>We are all familiar with seeing low-Earth orbit satellites scooting across the sky in a couple of minutes. Many of them are bright and readily identifiable with the naked eye. Geostationary satellites on the other hand are much further away and would remain fixed in position (though moving very slowly with respect to the background stars).</p>
<p>How bright are geostationary satellites in reflected sunlight? Can any of them be spotted, even with a telescope?</p>
<p>Related questions:</p>
<p><a href="https://astronomy.stackexchange.com/questions/34613/how-will-starlink-affect-observational-astronomy">How will Starlink affect observational astronomy?</a></p>
<p><a href="https://astronomy.stackexchange.com/questions/38663/how-do-satellites-impede-current-telescopes">How do satellites impede current telescopes?</a></p>

CC BY-SA 4.0
2020-09-01T14:29:14.897Z
Odd -- I'm pretty comfortable claiming that a geo-synch satellite or two, most likely TV providers ( my old dish pointed at one)  are pretty bright right around sunset and again around sunrise.  Bright as an inner planet.
Carl Witthoft
<artificial-satellite><apparent-magnitude>
How bright are geostationary satellites due to reflected sunlight?
ProfRob
# How bright are geostationary satellites due to reflected sunlight?

(Asked by: username_0 on 2020-08-31)

We are all familiar with seeing low-Earth orbit satellites scooting across the sky in a couple of minutes. Many of them are bright and readily identifiable with the naked eye. Geostationary satellites on the other hand are much further away and would remain fixed in position (though moving very slowly with respect to the background stars).

How bright are geostationary satellites in reflected sunlight? Can any of them be spotted, even with a telescope?

Related questions:

[How will Starlink affect observational astronomy?](https://astronomy.stackexchange.com/questions/34613/how-will-starlink-affect-observational-astronomy)

[How do satellites impede current telescopes?](https://astronomy.stackexchange.com/questions/38663/how-do-satellites-impede-current-telescopes)

**Tags:** artificial-satellite, apparent-magnitude
> **Comments:**
> **username_1**: Odd -- I'm pretty comfortable claiming that a geo-synch satellite or two, most likely TV providers ( my old dish pointed at one)  are pretty bright right around sunset and again around sunrise.  Bright as an inner planet.  

---

## 2 answers

### Answer by username_3 on 2020-09-01. Score: 4 | Accepted answer

* Have a look at [Is it possible to capture geostationary satellites with DSLR?](https://space.stackexchange.com/q/33891/12102)
* See the excellent advice in [this answer](https://space.stackexchange.com/a/12409/12102) to *Are any geosynchronous satellites visible with the naked eye?*

> No, but they are easily seen with a small telescope on a sturdy mount. March and September are the best times. Use an app to help you. **My favorite way is to keep M11, the Wild Duck Cluster, in view with a medium power eyepiece. Every few minutes, a "star" will slowly track through the southern edge!**

It's a **fun and instructive exercise** to calculate the declination of an equatorial GEO orbit from a given latitude!

* GEO satellites can be quite large, and while they are said to be +10 to +14 magnitude they can flare far brighter due to flat surfaces, both solar panels and thermal radiators. From <http://www.satobs.org/geosats.html>

> **Typically the satellite will be in the mag. +11 to +14 range (or dimmer), but brightening by several magnitudes when the geometry is favourable (around mag. +5 to +6 is not untypical). One satellite is reported to have briefly been visible to the naked eye at mag. +3!**

* See Richard Huziak's (Saskatoon Centre (contact info in link) excellent tutorial [Observing Geostationary Satellites](http://adsabs.harvard.edu/full/2000JRASC..94...14H) reprinted from Saskatoon Skies:

> ...**I found three other satellites, all between magnitudes 13 and 13.5, each a degree or two from the last!** Chances are that one of the satellites is Canada’s Anik C1, although I could not identify it for certain.

From Sky and Telescope's [How to See and Photograph Geosynchronous Satellites](https://skyandtelescope.org/observing/how-to-see-and-photograph-geosynchronous-satellites/)

> **Many geosynchronous satellites shine between magnitudes 10–12**, so you can spot them in telescopes as small as 4 inches. They're also easy to photograph. High ISOs and fast, low light lenses aren't necessary, just a camera capable of a several-minute-long time exposure — long enough for the stars to trail, so you can easily tell them apart from the satellites. Set your shutter speed to "B" and ISO at 400. You can hold the shutter button down with your finger, but a shutter release cable is much better and vibration-free. Use a 100–200-mm telephoto lens, focus sharply, and expose for 2–4 minutes. When you enlarge the image, you'll should see long trails and a line of pinpoint dots — satellites!

* **See and enjoy the videos of** ***GEO satellites colliding with space junk*** linked in [Are commercial communications satellites in GEO being constantly monitored by telescopes?](https://space.stackexchange.com/q/27436/12102)
* From [this answer](https://space.stackexchange.com/a/37454/12102) to *Are there any satellites in geosynchronous but not geostationary orbits?* we can see that while many objects in GEO have a well station-kept equatorial orbit, some are allowed a small inclination and others can have quite a large one!

[![synodic plot of GEO orbits](https://i.sstatic.net/SwR8L.png)](https://i.sstatic.net/SwR8L.png)

* Large communications satellites can have large flat surfaces that can dramatically increase their visibility at certain oriatiantations. These include solar panels that are often articulated to always point at the Sun, and large thermal radiators that have high thermal emissivity (are dark) in thermal IR yet highly reflective (mirror-like) in visible to avoid solar heating. For more on that see answers to [What are these very large, square panels on Inmarsat 5?](https://space.stackexchange.com/q/21524/12102) and [What is the function of this array of what looks like mirrors on TESS?](https://space.stackexchange.com/q/26544/12102) and some cool photos of spacecraft in question.
* For some math, see answers to [At what magnitude would adjacent large geostationary communications satellites see each other?](https://space.stackexchange.com/q/19382/12102) and [When would we detect a tiny meter size natural satellite in a geostationary orbits?](https://astronomy.stackexchange.com/q/29957/7982) and [Calculating the apparent magnitude of a satellite](https://astronomy.stackexchange.com/q/28744/7982)
* For a truly weird looking communications satellite bound for GEO see [Why do these satellite antennas look so weird? (strangely shaped with little white dots…)](https://space.stackexchange.com/q/37957/12102)

[![Shiny surfaces on communications satellite](https://i.sstatic.net/7GEH1.jpg)](https://i.sstatic.net/7GEH1.jpg)

[![Shiny surfaces on communications satellite](https://i.sstatic.net/n5yTM.jpg)](https://i.sstatic.net/n5yTM.jpg)

From [How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints?](https://space.stackexchange.com/q/20861/12102) you can see thermal radiators that are highly reflective in the visible (and near IR)

[![Shiny surfaces on communications satellite](https://i.sstatic.net/DYQT2.jpg)](https://i.sstatic.net/DYQT2.jpg)

From [How will GOES-R simultaneously point some instruments down at Earth and others sunward?](https://space.stackexchange.com/q/19064/12102)

[![Shiny surfaces on communications satellite](https://i.sstatic.net/4gc8C.jpg)](https://i.sstatic.net/4gc8C.jpg)

> **Comments:**
> **username_3**: not exactly related, but don't forget radio observations! [“Mysterious radio signals” - how could a geostationary satellite and Ross-128 line up with Arecibo?](https://astronomy.stackexchange.com/q/21753/7982)  
> **username_0**: Brighter than I expected. But then I guess, 100 times further away and 10 magnitudes fainter than low-Earth orbit satellites is about right.  
> **username_3**: @RobJeffries This was (obviously) fun to write ;-) if you (or anyone else) happens to spot one and can estimate a brightness, that would make for an interesting supplemental answer!  
> **username_4**: The October 2020 Sky & Telescope magazine has an article about observing them. Since they flare when the apparent declination of the satellite equals the Sun's declination, the flare "season" occurs near the March and September equinox. It has been years since I saw one, and it was through a car windshield, but I think they can easily reach second magnitude under the right conditions (date, time, and satellite design.)  
> **username_3**: @JohnHoltz Thanks! Consider adding another answer summarizing what's in that article, or please feel free to edit this answer.  

---

### Answer by username_2 on 2020-08-31. Score: 1

Geostationary satellites are often seen with telescopes and occasionally result in a
"Something Moved! Did I see a UFO?" sort of message.

If you have a tracking telescope aimed at a star in the same field if view of a geostationary satellite the satellite will appear to move against the background. It you turn off telescope tracking the satellite will appear to be stationary but the stars will move against the background.

Geostationary satellites come in various sizes shapes and reflectivity. No doubt the brighter satellites will be visible with binoculars.

Naked eye???

What a wonderful project for an aspiring astronomer. Sharpen up your Google, I will watch for your report.


---

