Celestron StarSense Explorer™ LT 80AZ Smartphone App-Enabled Refractor Telescope

StarSense Explorer: Your Phone Finds the Way

Celestron has reinvented the manual telescope with StarSense Explorer, the first telescope that uses your smartphone to analyze the night sky and calculate its position in real time, and it is ideal for beginners thanks to the app's user-friendly interface and detailed tutorials. StarSense Explorer uses patented sky recognition technology and your smartphone to work out where the telescope is pointed: a Lost in Space Algorithm (LISA), like the ones satellites use to orient themselves in orbit, matches the star patterns the phone detects overhead to the app's internal database.

Place your phone in the StarSense dock and launch the app. After you align the phone to the telescope's optics, a quick, 2-minute procedure, the app lists the celestial objects currently visible. Pick one from the planetarium view or the Tonight's Best list and arrows appear on screen to guide you; the bullseye turns yellow when the telescope has detected stars but is not yet on target, and green when the object is ready to view in the low-power eyepiece. Stop for a few seconds as you get close, so the telescope can sense the stars in its new position.

80mm f/11 Refractor Optics

The 80mm aperture and 900mm focal length give 131x the light gathering power of the eye, a limiting stellar magnitude of 12 and a resolution of 1.74 arc seconds (Rayleigh) or 1.45 arc seconds (Dawes). Fully coated glass optics increase light transmission. The aluminum tube is 965mm (38") long and 90mm (3.54") in diameter and weighs 5.4 lbs (2.45 kg).

A 90-degree erect image diagonal is included, so the view is upright and you can use the telescope during the day to watch birds, wildlife and landscapes. Expect sharp, bright views through this 80mm refractor.

Setting Up the App and Phone

Download the StarSense Explorer app before your first night out; the app is large, so a Wi-Fi connection is recommended. The unlock code on the card in the box enables telescope control on up to 5 devices. The app works with most modern smartphones, and Celestron keeps a compatibility list on its site; on older phones the app can still be used, but it cannot be reinstalled once uninstalled.

To align the phone, which is best practiced during the day, insert the low-power eyepiece, place the phone in the dock and turn the knobs at the bottom of the bracket until the camera view is centered, unobstructed, in the dock's mirror. Point the telescope at a very distant object, at least a quarter mile away, such as a streetlight, a license plate, a stop sign or a treetop, center it in the eyepiece, then slide the camera view until the same object sits in the crosshairs. If you have removed the phone from the dock since the last alignment, the app suggests aligning again.

To attach the phone, remove the large cap over the dock's mirror, pull open the spring-loaded slider on top of the holder, set the phone flush with the bottom lip and release the slider slowly. Most phones fit with the case on, but a bulky or folio-style case may need to come off. A small clear plastic tab between the dock's battery and its contact keeps the battery from discharging in shipping; pull it out before use.

Altazimuth Mount and Tripod

The LT's altazimuth mount is simple, making it easy to move the telescope to your target. To move left and right, loosen the azimuth tension knob on the yoke mount between two tripod legs, hold a leg and swing the tube by its focuser; the knob also sets how much tension you feel. To move up and down, loosen the knob on the slow motion rod guide, move the tube, and tighten it when you are close. With the rod guide knob locked, turning the black handle of the altitude slow motion rod moves the telescope in small increments to center objects or follow them. The rod has about 15 degrees of travel; at the end, loosen the rod guide knob, turn the handle back to the middle of its travel and retighten.

The tripod comes with the alt-azimuth yoke mount and center leg brace attached: spread the legs, push down the brace, extend each leg 6 to 12 inches so all three are the same height, and thread the accessory tray into the center of the brace. The tube's altitude hubs sit in the cradles on top of the yoke arms, the altitude rod slides into its guide, and two tube mounting screws go through the yoke into the hubs. The StarPointer fits over two threaded posts near the focuser, held by two silver nuts, and the phone dock's dovetail slides into the dock mount on top of the tube, held by two setscrews. The tripod reaches a maximum height of 1320.8mm (52") and weighs 3.8 lbs (1.72 kg).

Eyepieces, 2x Barlow and the StarPointer

The 25mm eyepiece gives 36x and the 10mm 90x; the highest useful magnification is 189x and the lowest 11x. To use the 2x Barlow lens, remove the diagonal, insert the Barlow into the focuser and put the diagonal into the Barlow: it doubles the magnification of whichever eyepiece you use, giving 72x with the 25mm and 180x with the 10mm. Always start with the 25mm eyepiece to find a target, then change to the 10mm. Focus with the knobs below the focuser. Magnification is the telescope's focal length divided by the eyepiece's. Find objects with the longest focal length (lowest power) eyepiece, which gives the widest field, then switch to the higher power eyepiece for a closer view. If bright stars twinkle or change color, the air is not steady enough for high magnification, and a lower power will give a steadier view.

Align the StarPointer red dot finder to the telescope during the day: center an easily recognizable object at least a quarter mile away in the low-power eyepiece, then, without moving the telescope, use the finder's two adjustment knobs to put the red dot on the same object. It should not need realigning unless it is bumped or dropped, and it is useful during the day or without the app.

Because the Earth rotates, objects drift across the eyepiece, faster at higher magnification. Celestron's Telescope Basics manual suggests positioning the telescope just ahead of the target and letting it drift through the field.

What You Can See

Even from a light polluted city, the LT 80AZ can pick out Jupiter, Saturn, Venus, the Orion Nebula, double stars and a few more of the most famous objects, and from even slightly darker skies more objects become visible.

Celestron's Telescope Basics manual suggests giving the telescope at least 10 minutes to cool to the outside air temperature, longer if the difference is large, and allowing about 30 minutes for your eyes to fully dark-adapt, using a red LED flashlight at low brightness if you need light. If you wear glasses, Celestron's Telescope Basics manual suggests checking whether you see the same field with and without them; if not, observe without them and refocus. For additional eyepieces, it suggests designs with at least 18mm of eye relief if you want to keep your glasses on.