Astro-Babys HEQ5 polar alignment page

OK you've aligned the reticule and now your ready to set the polar scope up to locate Polaris. Heres how....

If you want to go back to the previous page click Take me back to align the reticule

polar scope reticule The polar scope and its setting scales is a simple astronomical calculator which allows you to fix the position of Polaris and therefore the North Celestial Pole ( NCP ). There are three elements to the calculator; the reticule, the RA index scale and the date circle. For now we will ignore the longitude scale which will only be of use if you live in a time-zone other than GMT.

Now Polaris isn't actually AT the NCP but its near it. Polaris 'orbits' the NCP - thats what the circle around the NCP mark is. The small circle marked 'Polaris' is where you will place Polaris once the mount is aligned.
What we will do here is line the scope up at a fixed point in time when we know where Polaris will be. That will allow you to use the scales to know where Polaris is at ANY date and time and therefore be able to align the mount to the NCP

Set Polaris to Transit Point
The first thing you need to do is release the RA lock, look through the polarscope ( focus it as you require ) and turn the RA axis until Polaris is at the bottom of the view ( see fig 4 ). Now lock the RA down.

This is the point when Polaris is highest in the sky and its called a 'transit'. You may wonder why its at the bottom - well a polarscope is like any telescope and shows things upside down unless corrected with a correcting prism. The polarscope doesn't have a correcting prism so what your seeing is wrong way up.
setting the polarscope calculator circles
Set scales to ZERO
With the reticule showing Polaris at the bottom and the RA locked turn the RA Index Scale round until 0 is under the RA Index Mark.

Now turn the Date Circle until the longitude scale also shows 0 against the RA Index Mark. You should find that the Date/Longitude Index Mark is also in line if the mount is new. If not ignore it at this point and carry on. Your settings should look like Fig 5

Now with the RA scale at 0 against its index mark lock the RA scale using the RA Index Scale Lock as shown in Fig 6.

Setting the date and time
We now need to set a date and time for a known transit of Polaris. For the sake of this tutorial and ease of visibility on the accompanying pictures we are going to set a transit time of 23:00 on October 10th.
To set date and time simply turn the Date Circle ( Fig 7 ) until the date you require is in line with the time you require for transit. The date circle is divided into months and days with markers for every 2 and 10 days.
setting the RA scale You can see in Fig 7 the Date Circle being turned to its setting for the transit time of 23:00 on October 10th - i.e. the time shown on the RA Index
( 23:00 ) lines up with the Date shown on the Date Circle ( i.e. 10th of the 10th ) in Fig 8.

The RA Index has two sets of numbers. The upper numbers are for the Northern Hemisphere the lower numbers are for the Southern Hemisphere.

How do you know what time and date to use as a transit ?
To find out what time and date Polaris is in transit you will need either a star catalogue/almanac OR a quick way is to use a program called PolarFinder. You can get this free on-line from
setting the time/date circle on the polarscope

Using PolarFinder you can find a time for transits at your location and simply set up the polar scope circles on your mount for your own time and date. Remember to compensate for Summer Time or Daylight Saving Time and use GMT only if your in the UK.

Note: I would advise you ALWAYS scan any downloaded programs for virus/spyware threats before running them.
date/time and RA scales for transit and polar alignment Locking the Date/Time Index Mark
With the date and time set as per Fig 8 you now loosen the Date/Longitude Index Mark ring by loosening its set screw ( its a small recessed screw on the same ring as the index mark ) you will need a flat bladed jewellers screwdriver to release/lock this.

Unlock the ring that contains the Date/Longitude Index Mark and rotate it until the mark is opposite the 0 on the longitude scale as shown in Fig 9. Be careful as you do this you don't move the Date Circle. Now lock the Date/Longitude Index Mark by fastening the locking screw.

setting the date circles index mark The purpose of the two locking positions on the RA INDEX and the TIME CIRCLE is simply so you have a reference point if the circles get moved.

If the circles are moved simply set both circles Zeroes to their respective index marks i.e. RA Index Scale is set to 0 against the RA Index Mark and Date Circle is set to 0 against the Date/Longitude Index Mark. In these positions everything is calibrated and ready to use. You will see how on the next page.

OF THE POLARSCOPE.....Click Here to go to the next page.

For people living in a different time zone you may need to adjust for Longitude Offset - this is described below.
From the Sky-Watcher manual:
The alignment procedure requires that you set the Longitude scale to "Zero".
Depending on where you live, "Zero" can be anyplace between the E and the W on longitude scale, so first you need to determine where zero is for your location.
Your Zero point is equal to the difference between your actual longitude and the longitude of the central meridian of your time zone. To calculate the longitude of your central meridian, multiply your time zone offset from Greenwich Mean Time (GMT) by 15. For example, in Waterloo, Ontario, Canada (Eastern Time) the time zone offset is -5 hours. Ignore the sign and simply multiply 5 x 15 = 75.The longitude of the central meridian for the Eastern time zone is 75 degrees west. The actual longitude at the viewing location in Waterloo is 80 degrees 30 minutes West. Ignore the 30 minutes and just use 80 in the equation. Now it's simple, 80 - 75 = 5. Since 80 is greater than 75 the result is positive 5. That means Waterloo, Ontario is west of its Central Meridian. In this case, the zero point is at the "5" mark on the W side of the scale. If the location was east of its central meridian the equation would yield a negative value. In that case the E side of the scale should be used.