Poor guiding at meridian crossing?

[DaveS]

As I was imaging the Rosette last night the 'scope passed the meridian. actually I was able to go quite a way beyond.

When I started the run with the 'scope pointing well east the target was showing a symmetrical array of hits all well withing 2" of the centre, as I had when imaging M42 earlier. I looked at the display during the meridian crossing and saw the hits were now running in an oval above and below the target, looking about +- 3", the dec guiding trace in both PHD2 and eqmod showed the dec peaks considerably larger than they had been. Thinking the azimuth bight have been knocked out (Which would cause dec drift at the meridian) I paused the run when the latest sub came in and checked the drift but PHD2 said <1', which was as close as I'd had it before. Not wanting to risk making things worse I carried on and went away. When I came back for the last sub, with the 'scope now well past he meridian the the hits were much closer to the centre than they had been all night and the traces were the best I'd ever seen.

Sorry I don't have a screen cap as I didn't want to go poking things when I was getting in subs.

So what's going on? My thoughts this morning were to do with balance going from east to west with instability at the meridian. What do you think?

Not had the opportunity to process the subs yet, so we'll see what the image is like later.

[ronin]

Is this not the weight bias of the scope, on the path up to the meridian the weight is biased in say the forward direction when it flips the bias changes to rear.

[DaveS]

There was no meridian flip, I was imaging straight through the meridian.

Next clear night I'll have to to another drift as I think I may have knocked one of the legs, so I'll take the opportunity to improve the PA further.