Thanks Alan & Louie,
I could have done more subframes of Orion but I had guiding problems
caused by a broken tab on the guide cable from the lodestar to the mount.
A bit of masking tape was needed to hold it in place.
That plus the fact that Orion was disappearing into a brown haze over Melbourne made me switch targets.
Eta was very good late at night - my guiding went to 0.19 rms at times
& some of the subframes had below 3 arc seconds FWHM.
However the 30 minute subframe in Ha of Eta showed rotation of the stars
at the bottom of the frame on the opposite side away from the OAG.
The cause - my mount had shifted on the backyard ground & was no longer level.
I need a concrete slab or even better a pier mount.
It seems that every night of imaging is quite an adventure.
cheers
Allan