Telescope Mount Polar Alignment for Dummies

[admin]

Polar Alignment for Dummies... like me

To understand this a bit, in the north you must align to the North Celestial Pole (NCP) and in the southern hemisphere you must align (ie point exactly) your telescope to the South Celestial Pole (SCP) - see the diagram below by Dennis Nilsson (CC license).



At night the stars appear to drift overhead from east to west, completing a full circuit around the sky in 24 (sidereal) hours. (Of course, exactly the same motion occurs during the day, except that the stars are not visible due to the sun's glare.) This apparent motion is due to the spinning of the Earth on its axis. As the Earth spins, the celestial poles remain fixed in the sky, and all other points seem to rotate around them.

Why do you need to know this? Well, if the stars are moving around that fixed point, by having your telescope point to the Celestial Pole you are aligning the rotational axis of a telescope's equatorial mount to the rotational axis of the Earth - also called "Polar Alignment" as you are aligning to the Pole (whether North or South).



First things first:

1) level the telescope mount, preferably with a bubble level

2) make sure your telescope mount is properly level, and tighten all RA/DEC adjustment knobs



3) do a rough alignment (if you cant go to #4) - either point in the general direction lol, or use your polarscope


if you dont have a polar scope or dont know what to do skip to #4

4) light polluted skies? Make sure your telescope mount labeled N is pointed N in the northern hemisphere or South (S) in the Southern hemisphere! Check this accurately with a decent compass. You can even be more accurate by inputting your latitude and longitude to get your magnetic declination here:
GSC - Geomagnetism - Magnetic declination calculator



Get a rough alignment to polar North or polar South using a digital compass, or a protractor and some string and your LAT/LONG information.
You can use the latitude angles on your mount shown here but i found they were inaccurate to several degrees:



To adjust your scope to the right angle use the following screws on your mount:





Skip to 7) if you dont have a handcontroller / GOTO scope


5) Connect mount to a handcontroller and do a 1-star alignment if you can see only 1 bright star, or 2-3 star alignment if you can see many more brighter stars.

6) if you are clueless about 5 or your handcontroller has issues, and If you have a port out for a handcontroller with RS-232 serial/usb out you can use EQMOD (FREE) if you have an EQ based scope or Orion mount. EQMOD allows UNLIMITED points for alignment, and makes alignment easy (and very effective!) with your favorite ASCOM-compatible planetarium software

Or Alignmaster (after 30 day trial, $30):

Alignmaster von Matthias Garzarolli

works quite well

7) Conduct drift-alignment either with a illuminated eyepiece with cross-hairs, or with a webcam


This guide will be updated and improved with pictures and more detailed information shortly!


cheers

[roverich]

That looks great Gus ....I will be checking that program out ...It's right up my alley ...

[psonice]

That was great up to step 5, where I realised the guide was for motorised mounts

I'll do a similar guide for doing it the old fashioned way once I've figured it out myself, unless there's one around already.

[admin]

ok added more information for non-Goto scopes... no would be great to read yours too Psonice after all we all learn something from everyone

[LeoMeduna]

Nice explanation! Recently got an Orion Sirius EQ-G with refractor and am struggling a bit. Used to using 10" Dob.

[JohnP_1]

Thank you! I've been new at this for a couple of months now. I've been able to take photos of some DSO, however, I can tell my alignment skills need refinement.

[BobDob]

This thread is informational only. Please raise discussion in the open forum...