If like me you opened up your bright new shiny HEQ5 mount and found yourself stumped by the “Polar Alignment” instructions then this page is for you !!
Although this guide is written specifically for the Sky-Watcher HEQ5 mount the unit is very similar to other EQ5 and the EQ6 mounts so it should be applicable to Orion EQ mounts and many other types as far as I know. To check the HEQ5 out and to see if it is the mounting you have or to see where some of the parts referred to in the PolarScope set-up guide are clickthe diagram tab titled “HEQ 5 Parts Labelled” (to the left or at the top if using a mobile)
NOTE: Its easier to do this procedure without the telescope or weights on the mount. This puts less stress on the altitude and azimuth bolts both of which are quite soft and prone to shearing if placed under too much stress it also makes it less likely you will hit your head on the telescope tube and hit the telescope tube against the mount during the alignment procedure.
|GETTING THE POLAR SCOPE READY|
Before starting you will need to remove the covers for the polar scope. The front cover simply clips off, the rear cover has a screw thread. You must also lower the weight bar and rotate the mount through its declination axis until the polar scope is clear. You can check just by looking down the hole underneath the front cover.
|NAMING OF PARTS|
The first thing you need to do is get familiar with the parts of the mount around the polar scope set-up. I haven’t detailed the altitude and azimuth set up because that’s simple enough even for idiots like me but if your really stuck click the diagram tab titled “HEQ 5 Parts Labelled” (at the top). The polarscope is also simple BUT not well explained on most web pages or the HEQ5 Manual.
|ALIGNING THE RETICULE|
|Possibly the toughest and scariest job for a newbie on the HEQ5 is getting the reticule aligned correctly to the mount.
Trust me its not as hard as you might think and if you take your time and don’t rush quite a simple job.This is an easier job if done indoors with decent lighting and your adjustment tools by your side. You will need one Allen key to adjust the reticule using the reticule adjustment screws shown above. There are three of these around the eyepiece and you will need to slacken one and tighten the others to take up the slack slowly and bit at a time to get alignment. DO NOT TURN ANY OF THESE SCREWS MORE THAN 1/8 OF A TURN AT TIME or else the reticule may fall out. These screws are quite coarse and are adjusting the reticule by fractions of a millimeter – a small amount of turn make the reticule move quite a bit as you will see.I would also advise to do this with the mount set for zero elevation and with the polar scope almost horizontal. That way if you do end up having the reticule fall out it wont go too far.
The manual assumes you will have the mount pointed at Polaris but its far easier to do this task with the scope aligned to a distant object. I use a light on top of a distant radio tower but you can also use a small dot on a white card pinned to a wall. The further away the target object the better.
Point the polar scope at the target, using the altitude and azimuth screws on the mount to fine tune. When you look through the polarscope the central area has a cross-hair. Align this over your target as in Fig 1.
To correct this drift of the target from the cross-hairs use an Allen key to slightly loosen the reticule adjustment screw most nearly opposite the cross-hair in the direction by which the the target is ‘off’ i.e. in Fig 2 you would slightly release the screw nearest the 2 ‘o’ clock position. Now tighten the screw that’s nearest to the object you are targeting on. You will find the screws are quite tight and will tend to ‘click’ a little as they are loosened. I use these clicks as a guide in any event – remember never to release any of the screws more than 1/8th of a turn.
You need to adjust for HALF the distance that the target has drifted. As an example in Figure 3 adjust the target to be halfway along the red line.
Now release the RA lock and rotate the mount back to its original position and re-lock the RA. Realign the target on the cross-hairs and now release the RA and rotate the scope again.
If the target still drifts you will need to keep repeating this until the target stays on the cross-hairs as the mount rotates. With a little experience and taking things slowly you will achieve a good accuracy in quite a short time.
In these examples I have shown the target as drifting by a huge amount to illustrate the point. In reality you will find the drift is very small and quite easy to correct.
Once done I usually put a small amount of tightening to each Allen bolt and recheck. DO NOT OVERTIGHTEN as you will damage the reticule.
OK you’ve aligned the reticule and now your ready to set the polar scope up to locate Polaris. Heres how….
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.
Your almost there….the mount is now calibrated and now we are ready to set up and align on Polaris and thus the North Celestial Pole or NCP.
If you have carried out the previous steps this next section tells you how to set up the scope to align on Polaris ready for observing.
|ALIGNING TO POLARIS AND THE NCP|
Questions and Answers on this guide – the following are common questions I have been asked