Phasing with relative encoder

I am working on a telescope motorization with direct drive. I use relative encoders. Of course at first start, the phasing is made. My problem is to find a way to have no more phasing at every start. Is it possible, if the direct drive is still at the same position, to restart without the phasing, or if I know the angle between present position and position at switch off, to send a value for the phasing. The movement for the phasing at start is a problem for me, especially with a telescope of 500kg.

You will need either an absolute encoder or Hall sensors connected & set to use in Granity.