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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:
Have a look at Is it possible to capture geostationary satellites with DSLR?
See the excellent advice in this answer 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!
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!
...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
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!
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? and What is the function of this array of what looks like mirrors on TESS? 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? and When would we detect a tiny meter size natural satellite in a geostationary orbits? and Calculating the apparent magnitude of a satellite
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…)
From How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints? you can see thermal radiators that are highly reflective in the visible (and near IR)
From How will GOES-R simultaneously point some instruments down at Earth and others sunward?
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.
