Thanks Steve, Andy, Derek, Rick, Dunk, David & Gary – I appreciate your comments.
I have licences for a number of planetarium / observation planning applications, all of which are fantastic and which I thoroughly enjoy using. These are The Sky X Pro, Starry Night Pro, SkyTools 3 Pro and Sky Safari 5 Pro (iPad). To my knowledge, Nereid is only displayed by SNP and SSP.
On the 27th Aug frames I could not locate Nereid based on the position plotted in SNP, so I figured the sucker was too faint. However, the next day, when I plotted the JPL Horizons data in TSX, TSX showed Nereid in a slightly different location so I set up again on 28th Aug and sure enough, managed to find a good candidate. When I then plotted the position for 27th Aug I also found a good candidate in those frames from the previous evening. Yippee!
I used the J2000 coordinate system for all plotted positions to make sure I was comparing apples with apples.
Cheers
Dennis