Initial Mounting Checks Goto Mount

The first step in checking out a go-to telescope's mount is to go back and at least review the manual one last time. Is it time to head outdoors? Nope. Most go-to scopes are pretty user friendly these days, but it is a lot easier to learn to operate them inside under normal lighting than it is out in a dark backyard. Indoors, it is easy to see the telescope is pointing to the ground instead of the sky or is about to crash into a tripod leg. Let's do a "fake" go-to alignment indoors before facing down the real heavens.

To perform a fake alignment, follow the CAT manual's directions exactly. Actually, Meade's and Celestron's HCs will scroll instructions across their displays that are adequate to get the scopes aligned and tracking. Keep the printed instructions close at hand the first few times, however, in case the HC's necessarily abbreviated instructions are confusing. Before beginning, ensure the HC is plugged into the appropriate socket and the scope is connected to its power source.

If the telescope tube needs to be placed in some kind of home position before beginning alignment (check the dad-gummed manual again), do that now. Home position for GEM-mounted telescopes usually has the tube pointing north in declination (parallel to the RA axis at 90° declination) and the counterweight bar "down." Home position for forks often has the tube level and pointed north. How exactly is the tube placed in home position? It can be moved either by using the direction keys on the hand control or by unlocking the mount's locks and moving it manually. If the scope is moved by hand, do not forget to relock the mount's locks. Use a compass to point the tube or mount north as required.

Okay, here we go: Flip the power switch to "on." If all is well, the HC display should light up, and its initial message (usually the computer brand, NexStar, Autostar, etc.) will be displayed. If there is a power-on light, that should illuminate. If this does not happen, check the power connection, cord, and power source. When the scope is successfully powered up, initial tests can begin. As a first check, try pushing the HC's direction buttons (be sure the mount's RA and declination locks are engaged). Normally, a go-to scope, even one that has not been aligned, will respond to direction buttons, but what if nothing happens when a direction key is pressed? Double-check that there is power going to the mount power by observing the telescope's light-emitting diode (LED) or HC display. If that is okay, the problem is likely that the scope is slewing at too slow a speed for its movement to be obvious. Reference the manual for instructions on increasing slew speed, increase the speed, and try again. There are some go-to mounts, mostly GEMs, that will not slew until the alignment process is started.

Follow the manual's instructions to begin a go-to alignment. Even if the CAT is equipped with GPS, it will probably be necessary to enter time, date, and position manually during a fake alignment since most GPS receivers cannot get a fix indoors. If the scope is allowed to try to get a GPS fix, it will sit there listening for satellites for a long time before it gives up. To prevent that, reference the manual; a push of an "Undo," "Escape," or "Mode" key will usually stop the GPS fix sequence and allow manual data entry.

The first piece of data the HC will request is time. Where do you get accurate time? easy: look at your watch. Even when doing a real alignment out under the stars, entering time within an accuracy of a minute or two is more than good enough. The scope will also need to know the local time zone, and that will probably be what it asks for next. Follow the HC or manual's instructions to scroll to and select the correct time zone. The next entry will almost always be daylight savings time(DST)

status. Is DST off or on? If this is set incorrectly, the scope will stop 15° away from its alignment stars. Confused? Just remember: "Spring forward (on), fall back (off)."

The telescope will also need to know the date if it is to generate an accurate computer model of the sky, choose good alignment stars, and move close to those stars. Meade and Celestron generally expect date entries to be in the U.S. format, which is month/day/year. Some scopes do allow this to be changed to day/month/year if desired. Do not worry about complicated things like Universal Coordinated Time (UTC) dates or Julian days; just enter the current calendar date.

If the telescope is to stop near alignment stars, it also has to know where it is located on Earth's surface. Since GPS is not available indoors, tell the CAT where it is by entering the location's latitude and longitude. Perfect precision is not required. Simply enter the position of the nearest city. Not sure what that is? A list of latitudes/longitudes for major world cities is usually found in the back of the telescope's manual. If not, entering "find latitude and longitude of city" into the Google search engine will list numerous sites that will give latitude and longitude for towns and cities. Take care to enter north or south correctly for latitude and east or west correctly for longitude.

Most telescopes will ask for the alignment type next (one star, two stars, etc.). What do you choose when it does ask for "type"? This should be whichever method allows the telescope to pick its own alignment stars and move to them automatically. Do not choose "SkyAlign," as that requires the user to slew the tube to stars, and there will not be any visible stars indoors. Check the instruction book, choose the appropriate align method, and hit Enter (or whichever key or keys is called for). The HC will then usually display the name of the first alignment star it has chosen and begin slewing to it. Watch carefully and be prepared to stop the scope if it looks like it is going to do something crazy. A press of a direction key on a NexStar controller or any key except "Go-to" or a direction key on the Autostar will stop an errant slew, but be prepared to hit the power switch just in case. If nothing is wrong, the scope will move to point at the spot where it thinks the first alignment star should be.

To determine whether the scope has stopped in approximately the correct position indoors, use a star chart that shows where stars are for a particular date and time. A planisphere, a simple circular star chart that is often called a "star wheel," is perfect for this purpose. The round map portion of a planispherecan be rotated to set it for any date or time, day or night. If a planisphere is not available, virtual ones can be accessed online. A particularly good one can found at Once current date and time are set in the planisphere (just use the same date and time entered into the HC; do not worry about DST), it will show the positions of bright stars for that particular date and time. Even simple planispheres will show all the stars scope HCs will choose for alignment since these stars are always bright and prominent.

With the telescope stopped at its first go-to alignment star, take a look at the planisphere to see in which direction this star lies. If the scope chose Vega as the first alignment star and the planisphere shows Vega to be lying in the northeast, is the scope pointing roughly northeast? If it is, continue. If not? Make sure the planisphere is set up for the correct day and time (a.m. or p.m.). If the chart seems okay, check the HC to make sure date and time were entered correctly. Assuming the scope is pointed in roughly the correct direction, keep going. The HC will now ask for the star to be centered in the eyepiece or finder. Obviously, that is impossible inside. Do not worry about it. Just mash whichever buttons the manual's or HC's display specifies in order to proceed to the next alignment star.

When the telescope arrives at the place where it thinks the second star should be, check the planisphere again to make sure the CAT is pointing in the proper direction. Then, press the appropriate buttons to accept that star. The HC will then "think" for a moment and, if everything has gone as it should, will display an "Alignment Successful" message. A GEM may require more than two stars to complete an alignment; if so, allow it to pick and slew to these stars and accept them.

What if the hand control display says "Alignment Failed"? If the telescope appeared to point in roughly the correct directions for the stars it chose, don't worry about it. Indoors, the scope's exact pointing could not be fine-tuned, and that may have caused the alignment to fail. If, however, the telescope pointed in clearly the wrong direction or did something nutty, like pointing at the ground, something is obviously wrong. Reread the alignment section of the manual, power the scope off, and reenter the data in the HC, triple checking that the time, time zone, date, and latitude and longitude and their "signs" (E/W and N/S) are correct. If that does not help, the prime suspect (other than a defective scope) is power. Triple check the power cord, battery, and connections.

If the fake alignment was successful, try a fake go-to. With the aid of the manual, choose an object in the HC. It really does not matter much which object, just one that is above the horizon. A bright star is a good choice. How objects are selected for go-to depends on the scope model. Celestron NexStar controllers have a list of named stars in the menus available by pressing the HC's "List" button. Meades have a selection of prominent stars in the Objects menu, which is accessed using the Enter and Mode keys on the Autostar. Select a star that is shown on the planisphere and hit "Go-to" or "Enter" as appropriate to send the scope to it. If the telescope stops pointed in the proper direction, all is well. Power down the scope. If it does not, recheck the planisphere and try again.

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