Sometimes telescopes have certain monikers in their name that seem to only mean something to the initiated. Things like EQ (equatorial mount), AZ (altazimuth mount), and mm (millimeter) show up all the time in telescope names making them read like a string of random letters and numbers sometimes. All of these codes mean something and the more you learn, the easier it will be to parse out the exact meaning of the telescope name in one glance. SLT is another such designation but what does it mean? Super Long Telescope? Nope.
The term SLT stands for Star Locating Telescope or Star Location Telescope. This is a term for the newest brand of consumer telescope which focuses on high tech solutions to astronomy. SLT telescopes include computerized databases that allow your telescope to find and identify stars in the night sky for you. That’s right, no more guessing about which dot is which star, SLT telescopes can do all of that for you.
How Do They Work?
If this sounds amazing, that because it is. Star Locating Telescopes use cutting edge technology to accurately map the heavens for you and using that information, they can do a variety of things which will knock your socks off.
The most basic SLT scopes use a basic triangulation system to orient themselves to the night sky and once oriented properly, they know, from the database, where each celestial object should be in the sky.
Most of these telescopes work by having you point them at three bright familiar objects such as the moon, Polaris, and Venus to align itself. Once the telescope knows where it is, the database will overlay itself over the actual night sky and provide you with accurate information.
These databases usually ship with tens of thousands of celestial objects preprogrammed into their memory giving you a nearly endless supply of data points to find and learn about. Many of the top rated SLT telescope databases have 40,000 or more objects that come standard right out of the box.
Some telescopes require you to move them manually and focus on each part of the sky by hand and then the database will be able to tell you what should be there.
There is a new and fancier flavor of telescope, using GoTo technology, that can move and align itself using motorized parts to do all of the work for you. An SLT telescope paired with a fluid GoTo mount with tracking ability is one of the most advanced machines you can get on the market today.
What SLT Isn’t
SLT does not automatically indicate the presence of motorized GoTo features or automatic tracking features. GoTo and tracking telescopes are built upon SLT databases but the presence of a database does not mean that you are getting motorized mounts at the same time. This an important distinction to make because it would be a huge bummer to buy a telescope thinking you are getting one thing while recieving another.
The SLT features are just the database. While many SLT telescopes do include the automatic tracking and locating features, not all do. You may get an SLT telescope that requires manual alignment or automatic location but no tracking.
There are models which have automatic alignment, automatic tracking, and automatic identification but make sure to read the details carefully. SLT does not necessitate the inclusion of these features but some telescopes might advertise SLT hoping you think you are getting the rest of the features as well.
Other Feature Names
The automatic motorized mounts that move across the sky on their own with information from the database are called GoTo mounts. They literally “go to” the selected object. Once you select an object from the SLT database, the mount will move the telescope into position for you.
Then you have automatic object tracking, which is separate from GoTo mounts. Some GoTo mounts will only locate the object for you and will not work to keep the object in view during use. That feature requires automatic tracking. That will ensure that the computer and the GoTo mount continuously work to keep your selected object in your eyepiece for as long as possible. Sometimes this feature is also called automatic corrective motion or something similar.
While Star Locating Telescopes usually are paired with a host of high tech and automatic features, not all of them are. Knowing what kind of technology available will help inform you of the best way to make a decision regarding your next high tech telescope.