Thanks for your comments. When I put the target list together I selected bright host stars with exoplanets that exhibited large transit dips – ideal for those new to this aspect of astronomy. What I didn’t do. and perhaps should have, was check whether or not these were multi-planet systems. I have since come across several papers discussing possible ‘missing’ exoplanets using the Titius-Bode law to calculate orbits. Using this data and your suggestions ref planet size and transit depth I should be able to come up with a target list. Will also see what the Stargazers Lounge are planning.