Celestron COSMOS™ 90GT

Refractor telescope with 90mm (3-1/2") aperture and Wi-Fi® control

  • Celestron COSMOS™ 90GT



Our take on the Celestron COSMOS™ 90GT

by Eric Angevine

Aim your telescope via Wi-Fi

Your mobile device is your portal to the stars with the COSMOS 90GT. Just download the free Celestron Navigator App for Apple® or Android™, look through the database of over 120,000 celestial objects, and touch the one you want to see. Your selection is transmitted via Wi-Fi, and the telescope goes into motion and finds it for you. Whether you're a beginner, or you want to share the sky with friends and family on a casual stargazing night, there's no easier way to explore the stars.

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A versatile scope

The 90GT gathers in a lot of light through its 90mm aperture, so you can see a variety of objects in the night sky. Check out craters on the Moon, the rings of Saturn, the Great Red Spot on Jupiter, the Orion Nebula, the Hercules Globular Cluster and more. Using the included planetarium app, you may even see a few things you never knew existed!

A great start for budding astronomers

Celestron developed this telescope with learning in mind. It incorporates the eye nebula graphic from the educational television series COSMOS: A SpaceTime Odyssey, and is packaged with a cosmic calendar poster with images from the series and a mirror star diagonal. The LED lights that indicate a strong Wi-Fi connection incorporate the Spaceship of the Imagination image from the series as well.


  • refractor design with fully coated glass optics provides outstanding views of the moon, planets, nebulae and more
  • free COSMOS Celestron Navigator app lets you aim the telescope with Apple® and Android™ devices
  • includes StarPointer finderscope, mirror star diagonal, free planetarium app, and Cosmic Calendar poster
  • choose from the Navigator app's database of 120,000 known celestial objects
  • aperture: 90mm
  • 10mm and 25mm Kellner eyepieces included (1-1/4" diameter)
  • highest useful magnification: 213X
  • 91X maximum magnification with included eyepieces
  • 910mm focal length
  • light gathering power 165X that of the human eye
  • altazimuth mount and aluminum tripod included
  • accessory tray includes rubberized smartphone/tablet holder
  • Wi-Fi indicator light lets you know when you're connected
  • 37" optical tube
  • weight: 14.2 lbs.
  • warranty: 2 years parts and labor
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

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What's in the box?

Download owner's manual

  • Telescope optical tube
  • Small dust cap (for focuser)
  • Large dust cap (for objective lens)
  • Tripod
  • Accessory tray
  • Fork arm assembly
  • 10mm Kellner eyepiece (1.25") (with 2 caps)
  • 25mm Kellner eyepiece (1.25") (with 2 caps)
  • StarPointer finderscope and bracket assembly
  • 90-degree Diagonal mirror (with 2 caps)
  • Battery holder with storage bag
  • Instruction Manual
  • Cosmic Calendar poster
  • Cosmos info card

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.


Overview: The Cosmos 90GT Wi-Fi telescope by Celestron is the first 100% Wi-Fi-operated telescope for amateur astronomy. You can control the telescope using the free Cosmos Celestron Navigator app with your iPhone, iPad, or Android smart device. The Cosmos 90GT creates its own wireless connection, so it can communicate with your device in locations where Wi-Fi or cellular networks are not available. The telescope comes with two eyepieces, a StarPointer finderscope, a Cosmic Calendar poster, and a tripod with accessory tray for holding your smartphone or tablet.

Note: The Cosmos 90GT Wi-Fi telescope requires power and a compatible smartphone or tablet to operate. There are no manual controls on the unit. See below for power requirements and compatible devices.

StarPointer Finderscope: The telescope comes with a StarPointer red-dot finderscope which helps you to aim the telescope at a distant target. The finderscope must first be aligned with the telescope before use.

Kellner Eyepieces: The Cosmos 90GT features two Kellner eyepieces: a low power 25mm and a high power 10mm. You can choose which eyepiece to use based on the magnification and field of view you desire. It is recommended that you use the 25mm eyepiece when first setting up and aiming the telescope, then switch to the higher power 10mm eyepiece to get a closer look at the object.

Star Diagonal: The included star diagonal positions the eyepiece at a more comfortable 90° angle to the telescope. Because the telescope is designed for astronomical use, the image is inverted. You can use the telescope without the star diagonal, if desired, by simply installing the eyepiece directly to the focuser.

Accessory Tray: The telescope comes with an accessory tray which provides storage of extra eyepieces, as well as a rubber-lined tray for your smartphone or a small tablet.

SkyAlign Technology: During setup, Celestron's SkyAlign technology can quickly and simply align the telescope. By pointing the telescope at three bright objects in the sky, and entering date, time, and your location on the app, the telescope automatically and accurately aligns itself.

Power Requirements: The Cosmos 90GT requires a power source in order to operate. It comes with a battery holder for 8 "AA" batteries (batteries not included). You can also use the optional Celestron PowerTank, or a 12-volt DC source with at least 1 ampere of current to power the unit.

Cosmos Navigator App: To get the most out of your 90GT Wi-Fi telescope, you will need to download the Cosmos Navigator App from the iTunes App Store or Google Play. The app has a database of over 120,000 celestial objects, and helps you to locate planets, stars, and galaxies, plus asteroids, comets, and satellites, including the International Space Station. The app can simulate the night sky and create a custom list of visible objects based on your exact time and location. When paired to the telescope via Wi-Fi, you can hold up your device and identify objects instantly. If you tap the object on your device, the telescope will automatically locate and center the object in the eyepiece. You can also move the telescope up/down, left/right with the app on your smart device. The Cosmos Navigator app is compatible with iPhone, iPad, and iPod touch with iOS 7 or later, as well as Android devices with the Android OS Version 4.0 and up.

Cosmos: A Spacetime Odyssey: The telescope's graphics are inspired by the TV series Cosmos: A Spacetime Odyssey, which aired in the spring of 2014. The fork arm has a three-dimensional "Spaceship of the Imagination" (SOTI) design with LEDs that illuminate when the unit is connected via Wi-Fi. The Cosmo series "eye nebula" logo can be found on the refractor tube. A Cosmic Calendar wall poster with images from the TV series is also included.


  • Optical Design: Refractor
  • Aperture: 90mm (3.54")
  • Focal Length: 910mm (36")
  • Focal Ratio: f/10.1
  • Eyepiece Focal Length: 10mm and 25mm
  • Eyepiece Magnification: 36x and 91x
  • Highest Useful Magnification: 213x
  • Lowest Useful Magnification: 13x
  • Optical Tube Length: 39.2"
  • Light Gathering Power: 165x (compared to human eye)
  • Weight (with tripod): 14.2 pounds
  • Overall Dimensions:
    • Length: 37.25" (including eyepiece)
    • Maximum Height (on tripod): 56.375"
    • Minimum Height (on tripod): 36.375"
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