How to Set Up a GOTO Telescope for Astrophotography

Here is a general way in five parts of setting up a computer-controlled telescope on an altazimuth mount for astrophotography.

1. Roughly level the tripod. This is not a critical thing to do as this method uses alignment on two stars. But a little care must be taken to at least keep the tripod level by less than five degrees because you should not totally rely on the telescopes built-in software. Precise leveling is only necessary if aligning on one star only.


2. Make sure the telescope's finder is centred in the field of the telescope. To do this, make sure that the crosshairs are correctly centred by adjusting the finder with a distant object on the ground during daylight.


3. Put the telescope into its 'home' position. Where this is will depend on the make of the telescope. This will usually be due north or due south. Again, there is no need to perfectly accurate while doing this.


4. Choose the 'two-star' alignment mode. The 'auto' or 'easy' alignment mode can be selected, but you have to be careful as the telescope seldom goes to the exact position of the alignment star, just the general area. Do not select 'one-star' or even 'zero-star' alignment as these require a perfectly leveled tripod. You will always find at this stage that pointing accuracy is out by several degrees until you can find bright objects like planets or first magnitude stars and synchronize on them. First magnitude stars are easily visible at medium power in daylight.


5. The two stars should be on opposite sides of the zenith some 120 degrees apart in azimuth but not at the same altitude. Neither star should be within 20 degrees of the zenith. When you have centred on each star, you will need to inform the telescope's computer. The more accurately you centre the star, the better, because any small errors will be magnified as the telescope swings across the sky. Be aware that using a planet as an alignment star should be a last resort because the positions of objects in the Solar System are not computed as accurately as those of stars.

To ensure that your set-up is working properly, simply go to stars that you can readily identify and make sure that the instrument locates them perfectly. Once you trust the telescope to go to familiar objects in the night sky you can be sure that the telescope will locate unfamiliar ones every time.