Celestron NexStar 90SLT Computerized Telescope
Celestron’s advanced NexStar Star Location Telescope (SLT) has remained a popular choice among users for years, thanks to its blend of excellent optical performance, an intuitive computerized system, and a robust single-arm fork mount.
This telescope package includes a pre-assembled, height-adjustable stainless-steel tripod, a quick-release fork arm, the NexStar+ computerized hand controller, a 90mm Maksutov-Cassegrain optical tube, along with several useful accessories.
Designed for convenience, the complete telescope setup requires no tools, and the fast SkyAlign alignment process gets you observing within minutes. This makes the NexStar 90SLT an ideal option for spontaneous stargazing sessions as well as extended nights under the stars.
With the NexStar 90SLT, you can clearly observe details on the Moon’s surface, see the phases of Venus, spot Mars’ polar caps, view Jupiter along with its four Galilean moons, and enjoy Saturn’s rings. It also doubles as an effective terrestrial spotting scope for daytime and wildlife viewing.
Maksutov-Cassegrain Optical Design
The Maksutov-Cassegrain (MAK) is a catadioptric telescope, meaning it combines both lenses and mirrors in its optical system. Incoming light passes through a corrector lens, reflects off the primary mirror, then returns to a spherical secondary mirror before reaching the eyepiece. This design produces bright, crisp images with minimal chromatic aberration.

The Maksutov-Cassegrain design offers several advantages. Rather than using a separate secondary mirror, the MAK employs a reflective “secondary spot” applied directly to the inner surface of the corrector plate. As a result, the telescope does not need periodic collimation like a Schmidt-Cassegrain. Additionally, the smaller secondary spot enhances contrast, giving the MAK its well-known sharp and high-contrast views.
One consideration with Maksutov-Cassegrain telescopes is that the thicker and heavier corrector plate takes more time to reach thermal equilibrium compared to a Schmidt-Cassegrain of similar aperture.
The Mount & Technologies
Computerized Alt-Azimuth Mount – The NexStar SLT uses a single-arm alt-azimuth mount that smoothly tracks celestial objects as they move across the night sky. The mount is supported by a sturdy, pre-assembled adjustable steel tripod.
NexStar+ Hand Control – This computerized controller allows automatic slewing to any of 40,000 celestial objects at the press of a button. Its extensive database includes over 600 galaxies, 300 star clusters, and numerous double stars. Unsure what to observe? The Sky Tour feature automatically compiles a list of the best objects visible at your current time and location.
SkyAlign Technology – Celestron’s SkyAlign alignment system simplifies setup more than ever. Simply aim the telescope at any three bright objects in the sky, and the system calculates its position to locate additional objects automatically. No star knowledge is required–you can even use the Moon or bright planets. For more details about SkyAlign, visit here.
Power – Observe wherever you like. The NexStar SLT can be powered by eight AA batteries (not included), a PowerTank portable battery (sold separately), or a 12V AC adapter (sold separately). The internal battery compartment supplies power to the precision servo motors, ensuring smooth, low-vibration operation while eliminating cord wrap issues.
Accessories Included
The telescope comes complete with a StarPointer™ red dot finderscope, a star diagonal, and two eyepieces (25mm and 9mm). These eyepieces provide both low- and high-magnification viewing options. The star diagonal offers a more comfortable viewing angle and an upright image, while the StarPointer™ finderscope helps you quickly align and center objects in the eyepiece.
The NexStar 90SLT is designed to grow alongside you as your astronomy skills advance. It is compatible with Celestron’s latest accessories, including StarSense AutoAlign, the SkyPortal WiFi module, and PowerTank Lithium.
Starry Night Software
Your purchase also includes a FREE download of Celestron’s Starry Night software. This powerful astronomy program helps you explore the night sky, learn about celestial objects, and plan future observing sessions. Celestron Starry Night is widely regarded as one of the leading astronomy software packages available, offering detailed tools to explore our solar system and far beyond.
TECHNICAL SPECIFICATION
+
Optical Design
Maksutov-Cassegrain
Focal Length
1250mm (49")
Eyepiece 1 Focal Length
25mm (0.98")
Magnification (Eyepiece 1)
50x
Eyepiece 2 Focal Length
9mm (0.35")
Magnification (Eyepiece 2)
139x
Finderscope
StarPointer™ red dot finderscope
Highest Useful Magnification
213x
Lowest Useful Magnification
13x
Limiting Stellar Magnitude
12.3
Resolution (Rayleigh)
1.55 arc seconds
Resolution (Dawes)
1.29 arc seconds
Light Gathering Power
165x (Compared to human eye)
Apparent Field of View
1°
Linear Field of View (@1000 yds)
53 ft (16 m)
Optical Coatings
Fully Coated
Mount Type
Motorized Altazimuth
Accessory Tray
No Tool, Quick release
Slew Speeds
Nine slew speeds
Tracking Rates
Sidereal, Solar and Lunar
Tracking Modes
Alt-Az, EQ North and EQ South
Alignment Procedures
SkyAlign, Auto 2-Star Align, 1-Star Align, 2-Star Align, Solar System Align
Computer Hand Control
Fully Computerized / Flash Upgradeable
NexStar+ Database
40,000 Object Database
GPS
Optional SkySync GPS Accessory (93969)
Software
Celestron Starry Night Special Edition Software and SkyPortal App
☀️ Solar Warning:
➠ Never look directly at the Sun with the naked eye or with an optic (unless you have the proper solar filter). Permanent and irreversible eye damage may result..
➠ Never use your optic to project an image of the Sun onto any surface. Internal heat build-up can damage the optic and any accessories attached to it.
➠ Never leave your optic unsupervised. Make sure an adult who is familiar with the correct operating procedures is with your optic at all times, especially when children are present.