Polar Alignment of your Equatorial Mount

Introduction

The key to using an equatorial mount is polar alignment — aligning the mount so that moving the telescope in Right Ascension precisely mimics the motion of the sky. There are several reasons why this is necessary, depending on what you are planning to do next:

  • It allows you to find objects using the standard Declination / Right Ascension coordinates used by astronomers. While this is not, in fact, how you are likely to find objects with an inexpensive manual equatorial mount with manual setting circles, it is essential for computerized “go-to” equatorial mounts, which depend on this system.
  • Once you have found an object by whatever means, proper polar alignment makes it easy to keep the object in view while observing — only the Right Ascension slow motion control is needed to track the object across the sky; no further adjustment of Declination will be necessary.
  • For longer observing sessions or for photography, a motor on the Right Ascension axis will allow the telescope to automatically track the object you are observing, so no further adjustments will be necessary at all after the object is found.

Three Things to Understand

Beginners are sometimes intimidated by polar alignment — and, in fact, this fear is often the reason they purchase alt-az mounts instead of equatorial mounts.

Fear not. Polar alignment is actually quite simple. It just means pointing the polar axis of your mount precisely toward the North Celestial Pole. So you really only need to understand 3 things:

  1. What is the polar axis of my mount?
  2. How do I adjust where the polar axis of my mount is pointing?
  3. Where is the North Celestial Pole?

Let’s go through those now.

1.

What is the polar axis of my mount? The polar axis is an imaginary line drawn through the centre of your mount, at a 90-degree angle to the counterweight shaft, and passing through the main metal body of the mount. There may be a hole through the mount along this axis, or it may just be solid metal.

To confirm you have found the polar axis, use your mount’s slow-motion controls to move the telescope in both directions (Right Ascension and Declination). The polar axis is the line through the mount that does not move when you move the telescope in either direction.

Read that last sentence again — it’s going to be important. The polar axis does not move when you move the telescope.

2.

How do I adjust where the polar axis of my mount is pointing? Since the polar axis does not move when you move the telescope, you don’t adjust where it is pointing by moving the telescope. For coarse left-right pointing you can just lift the tripod’s legs off the ground and turn the entire mount and tripod, and you can do coarse up-down adjustment by adjusting the length of the tripod legs.

For fine adjustment, there will be controls on your mount to tilt the polar axis up and down, and probably other controls to move it left and right. These are separate from the controls that move the telescope on the mount.

That last point is so important that we’ll repeat it a couple of times. Polar alignment is done by moving the polar axis or by moving the mount itself, not by moving the telescope on the mount. The slow-motion controls you use to point the telescope are not used for polar alignment.

Here’s the repeat. Polar alignment is done by moving the mount, not by moving the telescope.

I see so many beginners making this error — trying to polar align by adjusting where the telescope is pointing, that I have developed an additional recommendation to help form the right habits. It is this:

The first time you set up and polar align your mount take just the mount outside. Don’t attach the telescope — leave it in the house, in a locked room. If possible, release a vicious animal such as a mongoose in the room with the telescope. (A Honey Badger also works well, but it can be difficult to persuade them to leave afterward.) This is so you are not tempted to think that you polar align by worrying about where the telescope is pointing. After the mount is polar aligned, go into the house, free the mongoose, and get the telescope and attach it to the mount.

3.

Where is the North Celestial Pole? The North Celestial Pole (NCP) is the point in the sky directly above the Earth’s North Pole. It is the point in the sky that does not move through the night or through the year — all the stars in the sky appear to rotate around this point. The NCP is very close to the star Polaris, otherwise known as the North Star. For many polar alignment purposes, you can consider the NCP to be exactly equal to Polaris.

This is why, if you own an equatorial mount, it is very important that you be able to find Polaris quickly — it’s your main alignment tool.

This is for astronomers in the Northern hemisphere, of course. Astronomers in the Southern hemisphere don’t have the convenience of a star located at the South Celestial Pole, and must use other nearby objects to estimate its position. Sorry, Southern neighbours, I have no experience to help you with that, but I hope the rest of this article is still useful. The “Polar Alignment Scope” method mentioned below, with a polar alignment scope marked for the Southern hemisphere, is your best bet.

How Hard Is It?

In that last point, we talked about the NCP being very close to Polaris, and implied that just pointing at Polaris may be good enough. That raises the question, “how accurate does polar alignment have to be?”

The answer is “it depends on what you are doing”.

  • For casual visual astronomy (i.e. just looking through the telescope for a short while, at a variety of objects) polar alignment doesn’t need to be very accurate at all, just a quick estimate.
    • Unless you have a go-to mount. Some go-to systems (like older Celestron and Meade systems) require moderately good polar alignment for the go-to to work accurately. Others, such as the Gemini system on Losmandy mounts, can compensate for inaccurate polar alignment.
  • For longer observation sessions, where you might want the telescope to stay pointed at an object for many minutes (e.g. studying one object, or displaying an object to a group of people at a demonstration) polar alignment needs to be somewhat accurate — enough to spend 5 minutes or so on the alignment before you start observing.
  • For photography through the telescope, polar alignment needs to be very accurate, depending on the type of photography. Serious astrophotographers planning to take long exposures might spend more than an hour on polar alignment before they begin their work. Permanent observatory installations may spend days on polar alignment.

Quick Polar Alignment for Casual Visual Use

Most of a beginner’s observing will be what I would call casual visual use. You will set up your telescope and spend one to three hours observing a variety of objects, then put it away. You’re not planning to be out all night, and you are not doing photography.

For casual use such as this, a very simple polar alignment is sufficient. Let’s discuss the most basic method, and then a slightly more accurate one. Neither will take you more than a couple of minutes with practice.

Most Basic: Compass and Latitude Method

The simplest polar alignment involves pointing the polar axis of the telescope to where the North Celestial Pole (NCP) “should” be, in theory, without the trouble of actually checking where it is really pointing. This is done by pointing the axis North and setting the elevation of the axis to equal your latitude.

First, determine your geographic latitude to an accuracy of about 1 degree. You probably already know this but if you don’t it is easy to find on the Internet. If you just Google on the name of your city and the word “latitude” you will probably get it. For more official data, Americans can check the US Geological Survey Geonames Server and Canadians can consult the National Research Council Geographic Names Server. United Kingdom residents and others can look up their locations at EarthTools, then click on the little teardrop symbol on the generated map to get their latitude & longitude. Google Maps can also display this information, although you may have to turn some options on first.

These days, the easiest way is with your smart phone.  Most have built-in GPS, and can be persuaded to tell you your latitude and longitude. Since they also record this information into photos taken with their built-in camera, taking a selfie, then learning how to query the location information in the photo, is another way, and much more trendy.

Locate the Latitude scale on your mount. Use the polar alignment elevation adjustment to set the elevation of your mount to be equal to your latitude.
Here I have set my latitude to 45 degrees for Ottawa, Canada. You don’t need to repeat this step unless you move a long distance or take your mount apart.

Get your mount pointing approximately North, then adjust the tripod legs to get the top as level as possible. Use a level if you have one available (or there may be a small spirit level built into the head of the mount) and adjust the tripod leg lengths until it is quite level.  (We did the rough North-setup first so that your tripod legs adjustment allows for being on sloped ground.)

Why did we do this? Because the elevation, in the sky, of the North Celestial Pole is, by definition, the same as your latitude on the planet. So now, assuming you have your mount level, the elevation of the polar axis is approximately correct.

Now, find North as accurately as you can. For this casual alignment, a good quality compass will do. If you know how to correct for Magnetic Declination, that is better still (this Silva Compass is shown corrected for the 14-degree magnetic declination in Ottawa).

If you don’t know what that means, don’t worry about it; just find North as accurately as you can. Polaris, the North Star, is a good reference. The advantage to the compass is that you can do your alignment before it is dark while Polaris, being fairly dim, requires that you wait until dark.

Point the polar axis of your mount toward North as accurately as you can. I like to stand back some distance and sight along my compass to the centre of the mount. This makes it quite easy to see if the direction is off.

In this photo, the mount is pointed too far to the right, so I just pick the whole thing up and turn it to the left, then check again with the compass, repeating until the polar axis is pointing straight North.

Reader Ian Wood has pointed out that, if you are not on level ground, picking up the whole tripod and rotating it will spoil the leveling you did a moment ago. He’s quite right. So, if you are not on level ground, you may need to cycle between pointing the mount North and leveling the tripod legs a few times, until you achieve both: the mount is pointing North and the head is level. Good catch, Ian, thanks!

That’s it. Your polar axis is now pointed to approximately where the North Celestial Pole should be (if it knows what’s good for it). This isn’t a very accurate method — it depends on the accuracy of your levelling, your latitude setting, and your North direction. But it is good enough for a couple of hours of casual observing.

Better: Sighting on Polaris

This next method is both more accurate and easier than the compass-and-latitude method described above, if your mount has a simple but important feature: a hole through the polar axis.

Many (not all) equatorial mounts have a hole bored straight through the mount along the polar axis. Examples of mounts that I know have such a hole include the Celestron CG-5, Stellarvue M4, Orion Skyview Deluxe, Losmandy G8 and G11, Skywatcher EQ3 and up, etc. Strangely, the expensive Celestron CGE-series mount (original version) does not have this hole, and relies entirely on the software method described below.

Note that, for now, we are talking about mounts where this hole is empty. On more advanced mounts there may be a small telescope permanently mounted in the hole, and that case is covered below.

The photos in this section are of a Celestron CG-5 (AS-GT) mount. Note that the telescope is not attached; polar alignment is done by moving the mount, not the telescope.

On some mounts the hole is obstructed when the mount is in a certain position and unobstructed in some other position. For example, the hole on this Celestron CG-5 mount is obstructed when the mount is in the normal rest position,

but when the Declination is rotated 90 degrees, the obstruction moves aside and you can see through the hole.

(This feature is so that you will rotate the telescope, if it is mounted, to a position where you are unlikely to bump it with your head when standing up after looking through the hole.)

Set the latitude on your mount as described above.
Roughly level the head of the mount as above. Then pick up the mount, tripod and all, and rotate it so the polar axis is pointing as close toward North as you can manage.
Now, wait until dark and find Polaris, the North Star. (That is, find it with your naked eye, not through the telescope. The telescope is locked in the house.)
Crouch down behind the mount and look upward through the hole in the polar axis.
Continue to adjust the up/down and left/right position of the mount until Polaris is centred in the hole through the polar axis.
Reminder: use the polar alignment adjustment controls to do this adjustment. You polar align by moving the mount, not by moving the telescope.

That’s it. If Polaris is centred in the hole through the polar axis, then the polar axis is pointed quite precisely toward the North Celestial Pole. This is much more accurate than the compass method above since you are actually pointing at the NCP, not just at where it “should” be. This is plenty of accuracy for an evening of casual viewing.

Better Polar Alignment for Longer-Term Visual Use or Casual Astrophotography

For longer-term visual use you need good polar alignment. For example, when I am participating in public outreach star parties, I like to take the time to do a good polar alignment. Then I can centre the telescope on an object and know it will stay centred (with a motor drive) for a long time, allowing a lineup of interested visitors to look without me having to interrupt them to re-centre. The polar alignment described in this section is also good enough for “casual astrophotography”, meaning photography with video cameras or with short exposure times (several seconds but not several minutes).

To get to this level of accuracy, we will be correcting for the fact that the North Celestial Pole is not precisely the same place as Polaris, but is offset slightly (about 1 degree).

You need the help of a tool to get good polar alignment. We’ll review two such tools here: a polar alignment scope, and the polar alignment software built in to many “go-to” mounts.

Polar Alignment Scope

Many equatorial mounts have an option to permanently mount a small telescope inside the hole bored through the polar axis. This polar alignment telescope is used to magnify the view of the sky around Polaris, and will contain an etched reticle to help you point your mount to the North Celestial Pole at its appropriate offset from Polaris.

As an example, here is a Stellarvue M4 mount with the polar alignment telescope mounted. You can see the eyepiece of the scope poking out of the bottom of the polar axis.
The polar alignment scope on this Losmandy mount has a small LED illuminator to make its internal reticle more visible against the dark sky.

If you look through a polar alignment scope, you will see some kind of pattern displayed on top of the view.

There may be several lines and labels that are for use by Southern Hemisphere astronomers. Use your instruction manual to determine which markings apply to you, and ignore the others. For the rest of this discussion, we’ll use just the Northern Hemisphere markings.

Note that the place for Polaris is not in the centre of the scope. Since it’s not in the centre, it matters which side of the centre it is on.
That’s what the small pictures of the Big Dipper and Cassiopeia are for. You will rotate the polar alignment scope (or the mount, depending on your equipment) until those two constellations are in the same position in the scope that they are in the sky, then put Polaris in the marked spot.

For example, tonight if the Big Dipper is to the left of Polaris, and Cassiopeia is below and to the right, you would rotate the polar scope to match that configuration.

(On the Losmandy, the polar scope can be rotated in the mount housing. On the Skyview Deluxe and Stellarvue M4, the polar scope is fixed in place, so you rotate the entire mount on the Right Ascension axis.)

Get it reasonably close to matching the position of the two constellations in the sky, but don’t obsess over it. This will be accurate enough for most purposes and, if you have a dark sky, you will be able to fine-tune using two stars in the polar scope (below).

Manually align the polar axis (by moving the tripod and then the fine up/down, left-right controls) until, crouching down under the mount, you can see Polaris in the field of view of the polar finder scope.

Then adjust your mount’s up/down and left/right fine controls until Polaris is in the spot indicated.

If you have the constellations lined up with their approximate locations in the sky and Polaris in the spot indicated, this is quite a good polar alignment already, and you may wish to stop here.

If you have very dark skies, you may be able to see a second, very dim, star in the field of view. This is Delta Ursa Minor, and most polar scopes also give you a marked spot for that star.

There may be several lines marking different spots for Delta. This is because of the slow movement of the stars near the NCP (because of the wobble of earth’s orbit called “Precession”). The lines will be labelled by year, and you should choose the target location closest to the current year.

Chances are that Polaris is in place but Delta is not. This indicates the rotation of the polar scope to match the position of the sky is not quite right, so you will need to rotate the Polar scope (or mount) slightly.

You continue to make fine adjustments to the up/down and left/right of the mount, and fine rotations of the polar scope, until these two stars are in the marked spots.

This gives an excellent polar alignment, good for any application except long-exposure astrophotography.

Polar alignment feature in Go-To mount

If you have a modern mount equipped with a “go-to” feature, or digital setting circles, you probably have another option to improve the accuracy of your polar alignment. Most such systems have a “polar alignment” routine available in their software.

This method is the sole exception to my suggestion about locking your scope in a distant room when polar-aligning: it does depend on looking through the scope. Because you will get confused about which controls to use (scope slow motion vs. mount adjustment) I don’t recommend beginners start with this method — use one of the more basic techniques described above for a while first.

Personally, I find polar alignment with a polar alignment scope faster and more convenient than a mount’s polar alignment software, and sufficiently accurate for most purposes, so I rarely use the software feature on mounts that have a polar alignment scope. On my permanently-mounted observatory mount, on the other hand, this is how I establish a “pretty good” alignment before going on to harder and more precise methods.

The specifics of these systems are quite different among brands, so I won’t try to give specific instructions here — read your manual. The general idea, however, is:

  1. Start by polar aligning your mount in the best way you can without the software — the more accurate you are to start, the faster the rest of this procedure will go.
  2. Do whatever sky alignment your mount’s go-to system requires. This usually involves slewing to, and precisely centring, two or three known stars at different locations in the sky.
  3. Invoke your mount’s “polar alignment assistance” feature, whatever it is called. Since use of this feature will require moving your polar alignment controls, which will cause the mount to lose the sky model it has established so far, there are usually some “are you sure?” questions to answer before the software will start this feature.
  4. The mount will slew to where some star should be if the mount is perfectly polar aligned. With some mounts, this is Polaris, and with others it will be a star elsewhere in the sky (or you may be asked to choose a star first).
  5. You then use the mount’s polar alignment controls (not the electronic controls on the hand controller) to make fine adjustments to perfectly centre this star.
  6. Some systems repeat this with more stars.
  7. Once you indicate to the mount that you are done, you will need to re-do the go-to system alignment.

Using Go-To for polar alignment without software feature

In fact, you don’t really need software polar alignment features in your scope. You can do this manually with any go-to scope.

  1. Polar align as best as you can in some other way.
  2. Set up and align the go-to system in whatever way the mount requires. If you have the option, use alignment stars that are far from Polaris.
  3. Go-To a star near the pole — but don’t use Polaris (it’s too hard to hit on an equatorial mount). I like to use one of the stars in the Big Dipper, like Dubhe.
  4. You’ll probably be close to, but not directly on, the target star. Use the mount’s polar alignment controls (not the telescope motion controls) to centre your target star in the eyepiece.
  5. Reset the mount (power off and on) and re-do the go-to alignment.

This generates quite accurate polar alignment, depending on how carefully and precisely you centre the target stars (use high magnification and an eyepiece with a target reticle if you want to really get this right).

Precise Polar Alignment for Long-Exposure Astrophotography

If you want to do long-exposure astrophotography, or are setting up an observatory with a permanently-mounted telescope mount, you need polar alignment that is as close to perfection as can be obtained. There is really only one way to get this level of accuracy: Drift Alignment. It’s not hard, but it’s time consuming, so it’s probably not something you’ll do unless you need it.

Drift alignment sounds very complex when you read instructions on how to do it. Conceptually, though, it couldn’t be much simpler. The idea is that, if your mount is perfectly aligned and you have an accurate motor drive, stars should remain perfectly still in the field of view of your telescope. Drift Alignment is just watching if this is happening (i.e. if stars are drifting in the field) and, if it isn’t, correcting your alignment until it is.

You do this by polar aligning by some other means, then pointing at a star that will show the most drift if alignment isn’t perfect (that is, a star that is far from the North Celestial Pole).

Usually, we start with a star in the Southern sky, close to due South and at an elevation near the Celestial Equator. This maximizes the drift caused by left-right errors in polar alignment. We observe it at high magnification, with an eyepiece with a reference reticle, for a long time — 5 minutes to much more depending on how picky you need to be. Drift of this star can be corrected with fine adjustment of the mount’s left-right polar adjustment controls.

Then we use a star near the horizon close to due East or due West, let it drift, and correct by adjusting the mount’s up/down polar adjustment controls.

There are many well-written descriptions of drift alignment already on the ‘net — Google will find hundreds, so I’m not writing another one here. Some of the guides I recommend are:

Drift Alignment Software

The real secret to drift alignment, however, is to use software and a camera to assist you.

Since you wouldn’t be bothering with drift alignment except for photography purposes, it’s reasonable to assume you have a camera and computer connected to your scope. Under these circumstances, very precise drift alignment becomes simple: you use software that uses the attached camera to monitor the drift and guide you in adjusting it.

(“Camera” in this context means a camera that can be operated by the computer — either a webcam, a dedicated CCD camera, or a DSLR with appropriate computer control. A DSLR that you must operate manually will not work for software drift alignment.)

I tried a few such packages and quickly settled on PEMPRO. Its primary purpose is measuring and tuning the periodic error of an equatorial mount, but it also has a polar alignment feature that is really easy to use.

After a bit of calibration, you just let the software watch a star for a while and, based on that star’s drift, it determines how you need to adjust your azimuth alignment. Then it helps you to make the necessary alignment by giving you a target on a star field, and you use continuous camera exposures to track your adjustment. You then repeat this with a different star to adjust the altitude alignment. It really couldn’t be much simpler, and I find I can do a very good drift alignment in about 45 minutes. PEMPRO isn’t free, but I find it is worth the price ($149), there is a free trial, and there is excellent support (by which I mean a user group in which the actual software author responds to questions and makes helpful suggestions).

WCS is another inexpensive package with a free trial. For me, since I needed the other functions of PEMPRO, the choice was easy, but WCS was also recommended by many users when I searched for recommendations.

Pointing analysis software on advanced mounts

At the very high end, specialized software that improves the pointing accuracy of the sky model on a Go-To mount (TPoint for TheSkyX and MaxPoint for Maxim DL) can produce a very accurate analysis of the quality of your polar alignment, and give very accurate instructions for adjusting it. (If you have a mount capable of being adjusted this way, and one of these software packages, you don’t need the advice in this article.)

47 comments

  1. People who are versed in celestial navigation use the term “magnetic variation” not “magnetic declination”. When converting a magnetic direction to true the rule is CDMVT to using compass, deviation, magnetic, variation, true. Each value is added or subtracted when converting to the next, always adding east, subtracting west. Deviation is to correct for errors arising from the magnetic influences of the vessel. For this purpose it would be zero. I see the term magnetic declination being used where the term variation is more accurate. I wish people would get it straight.

    1. I read Richards dissertation on how to polar align an equatorial mount for a telescope with great interest and was delighted that he used respect and restraint when talking to an uneducated newbie like me. My only disappointment was when reading your confusing comment about magnetic declination vs variation. KISS works for me, lets get it right.

  2. Is it safe to use an equatorial mount on low latitudes? I am considering buying a telescope (my first) and I was reading the manual for Celestron 127EQ (which I think is fair bang for the buck for a first-time telescope) online and it says that the latitude meter has a range between 20-60° and I am below 10°N (in Costa Rica) so I am very hesitant on going for it. I guess I could use a cellphone to get it aligned (have seen it on some videos) but I wonder if the counterweight will allow me to get the mount that low or if the telescope would trip over because of the weight being outside of the base of support because of the low angle while aligning it. Do you have words of wisdom for my situation?

    1. También estoy buscando mi primer telescopio, así que no soy un experto, pero por lo que sé no debes tener ningún problema, lo puedes usar en cualquier parte del planeta, solo que no podrás usar el primer método de alineación descrito aquí porque la escala de latitud en la montura solo llega a 20°. También será difícil ver Polaris, va a estar muy cerca del horizonte. Tal vez te convenga pagar más pero tener una montura computarizada que lo haga más fácil. Por cierto, será por el COVID o será por las fiestas navideñas pero muchos telescopios están agotados y se empiezan a enviar hasta ya entrado febrero.

      1. Gracias por el feedback, Eduardo. Compré un telescopio con base equatorial y funciona bien. Lo del ángulo no es mayor problema. Utilizo mi celular para mirar el ángulo y también para apuntar al norte así que creo que queda razonablemente alineado para un principante. Y no me extraña lo de que no lleguen hasta febrero… entre black friday, navidades y la gran conjunción de saturno/jupiter, seguro los stocks iban a quedar agotados.

        —-

        Thanks for the feedback, Eduardo. I bought one with EQ mount. The angle is not a major issue. I use my cellphone to measure the angle and to point north so it is reasonably aligned for a rookie. I am not surprised with the telescope arriving in February. Black Friday, the great saturn/jupiter conjunction and xmas were going to deplete stocks.

  3. Can someone tell me what the make and model of the mount is that used in the photo captioned:

    “Here I have set my latitude to 45 degrees for Ottawa, Canada. You don’t need to repeat this step unless you move a long distance or take your mount apart.”

    I purchased mine a number of years ago second hand and it did not come with any identifying marks. I need to purchase a northern hemisphere polar alignment scope for it and am at a loss for sources. This is the only website I can find that has the exact mount I have.

    Please help. Thanks!

  4. One quick, and probably very stupid, question; if you have the counterweight bar pointing straight down in line with the front tripod leg, in the polarscope would polaris be at the 6 o’clock position on the reticle?

  5. Hi,
    Text is great as is the photographs.
    One question, in the first “movie” the telescope is always pointing at the same point in the sky. I thought the axis of telescope revolution should be through the counterweight axis. This would allow the telescope to traverse from horizon to horizon. Am I correct?

    1. That movie is showing the telescope looking towards the north celestial pole so it will look at the same bit of sky all night. The RA movement shown simply adjusts for the field rotation. The axis through the counterweight is the Declination.

  6. Sir, I had hard time to understand the polar alignment… But now I do, very clear and understandable explanation… Thx so much

  7. Many thanks for this help online to us novices in astronomy. The explanation and scope of the writing is very informative and a great resource.

  8. This is a great write-up. It’s very thorough and easy to understand. I’ll definitely be taking this with me next time I set up my new Celestron and polar scope. Thank you.

  9. I refer to your section “polar alignment feature in Go-To mounts”: There is a simpler way which I have successfully used for astro photographs up to 4 minutes with Sky Watcher’s ALT-AZI EQ-5 mount and their 400mm / f:5 scope with Nikon’s full frame D-750 camera.
    The first part is to align the telescope axis exactly parallel to the RA rotation axis. The telescope has 2 degrees of freedom: One is the rotation of the declination axis and the second is the angle of the dove tail relative to the RA axis. By rotating the RA axis and observing via the camera’s monitor a far away target one moves the declination axis to a point for minimum drift of the target from centre. Then one uses shim pieces under the dove tail receptor plate to minimize the targets’ drift in this direction. Some dove tails have already set screws to avoid use of the shim pieces. By conveniently repeating these two steps at daytime one can achieve a cone angle of nearly zero. To maintain these positions one can permanently lock the the clutch of the declination axis and rotate the axis only via the drive motor. A good fitting dovetail provides the second lock point, so that these settings can be reproduced after the telescope is transported.

    To take photos the Go-To system is activated similar as you described. The mount is set level, the scope points roughly north, the altitude (for location)is set with an angle locator on the scope, the counter weight points down and the clutch of the RA axis is locked. This position is used in “start from home position?” in the computer program. The date,time,location and sidereal tracking are entered as usual. The computer now assumes that the mount is perfectly aligned, which it is not of course. One can now skip the usual alignment procedure and go right to “find object”. Any star with known coordinates can be entered and the GO-To activated. Of course the star will not be in the centre of the camera’s field, so one uses first the mount’s azimuth screws and then the mount’s altitude adjustment to bring the star into the centre. That’s all. The advantage of this method is that seeing Polaris it not necessary.

  10. Thank you, so much, for a straight forward explanation on polar alignment. I’ve read a few explanations on the web, but yours was the first one that made sense. Also, I appreciated your humour. Your mongoose and honey badger comment really amused me, I was in fits of giggles!

  11. I’m new at this so bear with me.

    If a person is using a telescope that doesn’t have a motor, what’s the need to Polar Align?

    1. If your telescope doesn’t have a motor, it will have two flex-arm slow-motion controls, like the small one shown in the first couple of images in this article. Polar aligning will mean that, once you have found your target, you can track it by moving only one of the slow-mo controls (the RA) control, rather than having to constantly adjust two.

      1. Thanks, Richard. So, this is true even though I have to manually move the telescope 180 degrees so I can look at the southern sky?

        1. Yup. As long as you polar-align the mount and then don’t move it, you can point the telescope anywhere in the sky and use just the RA control to track your target. (Remember the motion controls you use to polar align are not the same as the motion controls you use to point the telescope.)

  12. Thank you so fuc**ng much. Finaly, someone explained this sh*t! All I could find until now are some stupid manuals that explain nothing. Just fuc**ng theory about polaris and azimuths and I don’t know what. I just want to point this thing to polaris, not become fuc**ing stephen hawking! cheers mate!

  13. Very Nice Richard. For fun I have just gotten a cg-4 mount on which I have a 5″ reflector. It has a polar scope, but Celestron only ruled it with the offset circle and a small Polaris circle. How can I set the thing to the proper hour angle so the polaris circle is correctly oriented?

    1. Google “polar scope calculator” and you can find several websites and phone apps that will take date, time, and location, and tell you where the offset direction should lie. Warning: some of them compensate for the inverted image in the scope, some don’t, so check that carefully.

      1. Right, found two. The free one (!) correctly portrays the inversion, though the other has more information displayed. So, I guess alignment goes like thi:
        1. Put scope in polar home – DEC = Lat, RA =0. (after leveling and so forth)
        2. Use alt-az adjustment to put polaris in center of polar scope to start
        3. Rotate the polar finder to put polaris circle ruling at the correct hour angle
        4. Use alt-az adjustment to place polaris in the circle

  14. Thanks for this wonderful explanation. Very helpful! Finally I understand this enough to properly setup my daughter’s reflector telescope!

  15. Wife bought me a telescope at Christmas and this article is far better at explaining polar alignment than the handbook that came with the scope. Many thanks

  16. very useful article…thanks a lot…i would appreciate if you explain other method you know for polar alignment…one of them that i know is polar alignment with finder that is a rapid way

  17. Very helpful article. I live(in Maldives) just north of the Equator(4deg) and my EQ5 mount’s polar axis cannot be lowered below 30deg because of the small bar that holds the bendy adjuster screw. If i removed the bar the axis can be lowered a little lower until the weights catch the front leg of the tripod. My only option seems to be to lengthen the southward legs until the mount is aligned, which could pose stability issues. It’s a dilemma. Any ideas would be much appreciated. Cheers.&|60;:)

  18. Great article, but there is one important thing missing before starting the polar alignment that is aligning the reticle in the polarfinder itself.

    If this isn’t aligned to the RA axis, the alignment of the polarfinder isn’t accurate.

  19. Just wondering. How important is the “level-ing” part of the alignment. I assume as long as the polar axis of my mount is polar aligned (and the other axis it perpendicular to that because of the way the mount is constructed) then should be all that is required. I can see that level-ing might help with distributing the wait on tripod, mount etc and also to get into the right ball-park for the “elevation of your mount” adjustment part…

    1. You’re right. As long as he polar axis is pointed at the NCP the base of the mount could be nailed to the side of a tree. Levelling is not part of the final result, it’s just a technique to help you achieve alignment, by making the latitude setting equivalent to the appropriate mount altitude. Levelling also makes the mount altitude less sensitive to rotating the mount by moving the tripod legs. But once you’re aligned, levelling of the base is irrelevant.

  20. Excellent article, I am at last polar aligned and get a great view of Polaris. All I’ve got to do now is work out how to turn the damn thing around to point at Jupiter.

  21. AT LONG LAST I KNOW HOW TO POLAR ALIGN.EVEN THE BOOKLETS THAT COME WITH THE TELESCOPE DO NOT EXPLAIN IT AS YOU HAVE.

  22. +1 for the mongoose. I bought a beautiful telescope, mount and motor drive with which I captured a few snaps of HaleBopp and then turned into furniture. It’s time it came back outdoors, and this helps a lot.

  23. Thanks for the article, I’m very new to astronomy and this has helped me get off the ground. I do have a couple of issues though: Once my polar alignment is complete and still in position, what do I set the Declination dial too? Is it 90 degs? Also, how do I get my right ascension dial aligned?

  24. Thank you for taking the time and effort to post this. I have a manual EQ mount and I’m thinking about purchasing a new scope with a powered EQ and computer drive…all that fancy stuff. This really helped a lot with my decision because I want to do photography and now I know what I need.

    And just wondering…as I’m sure others are too… Do you have a mongoose?

    Thanks again.

  25. Fantastic article, makes it all very clear, one question for anyone to answr plse, In the “Better: Sighting on Polaris” it tells us to set latitude and but later on when sighting Polaris to ” Continue to adjust the up/down and left/right position of the mount until Polaris is centred in the hole through the polar axis” isnt the up down adjustment changing the latitude? thanks

    1. Yes it is. The initial “set latitude” (and the initial leveling) is just to get the mount into the approximately correct position, to increase the chance that Polaris will be inside the sighting hole.

  26. Polar alignment is done by moving the mount only is very informative to me. Once The polar alignment is complete, how do I view an object in the Southern Sky. My Latitude is 30° and the mount is polar aligned at that setting. If I look North or South at an object (star) that requires an altitude setting of 35°, doesn’t that change my polar alignment. Thanks for the opportunity to read your article.

    ojolly2@comcast.net

  27. Polar alignment is done by moving the mount, not by moving the telescope.

    Polar alignment is done by moving the mount, not by moving the telescope.

    Polar alignment is done by moving the mount, not by moving the telescope.

    This is the most important message for me.Thank you very much, it makes so much sense to me.

  28. Thanks a lot for your valuable,highly useful article on Polar alignment. Most tutorilas are confusing for a beginner like me.

  29. I found your page was very helpful in learning how to polar align my scope. all the other tutorials i read were confusing, but you made it very simple and easy to understand. explaining the different ways you can align and why you might want to align it that way was also informative and helpful. Thanks!

  30. Great article, we just need a similar one to cover setting up in the southern hemisphere, where they do not have a bright star like Polaris close to the pole.

    One comment on the latitude angle marks on many mounts, use as a rough guide only. A refinement is to use a protractor with a level and a fine plumb bob line.

    A great alignment tool is Andy’s Shotglass StarTarg 2.0: http://www.andysshotglass.com/StarTarg.html, which has a simple tutorial on its use.

    http://www.shevillmathers.id.au Southern Cross Observatory

  31. THANK YOU!!!! SOO MUCH. I have just purchased a celestron Powerseeker 127 eq.I have had a thousand walmart telescopes and have never had the opportunity to have something like this. The Mount has had me mystified because I am so excited to just find what it is I’m looking for and in all my hurry I couldn’t get the polar alighnment right. I didn’t think to move the whole mount(not the telescope).directions on Setting the altitude helped too. I am truly a beginner and you were quite helpful.

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