Saturday, October 1, 2016

My backlash issue in DEC

As I wrote before, I observed a pretty severe backlash in both axis. When I asked about this in astro-phyisics forum, I got a talking to from Roland that this is a red herring. Well, I still tried to fix it.

I used the Guiding Assistent from PHD2 which can also measure DEC backlash:

And PHD2 measured 1008ms backlash compensation!!!

After I entered this in the backlash compensation settings, I had a couple of "overshootings" where PHD2 correct in DEC so much that the star went to the other side. I asked my friend Tim Kahn about it who told me to only use 60% of the correction to avoid this. I did that, and since then have MUCH better DEC corrections.

I still wonder if I never noticed that before (would be strange) or if something really changed in the mount...

But the result is that I can now track REALLY well. I get 0.5 arcsec accuracy on pretty much all nights now.