Here’s something I haven’t seen before.
I was imaging a target close to the
meridian with the Mach 1
DEC balanced camera-heavy. The PHD2 log showed a lot of oscillating corrections in
DEC during the first 10min exposure, decreasing with time. They’re red in the screenshot from PHD2LogViewer, highlighted with the white lines. (There were four dithers during the session, marked by the spikes in the guiding corrections.)
My take on this is that the session started when the target was passing through a zone where the camera-heavy balance in
DEC was shifting from south to north, and it took about 10min for it to settle to one side.
DEC backlash correction was on, but I’m thinking that guiding was busy keeping up with the shifting balance between north and south. Even with this sketchy beginning, the total RMS error for the session was 0.74”. (I usually do better!)
There’s radial asymmetry in my
OTA/focuser, so I’ll rotate the
OTA to keep the
DEC balance to one side, even for a few hours past the
meridian. And dream about getting the Mach 2, which has encoders….
Does this seem like a plausible interpretation?
Thanks,
David