Helene resides in the leading Lagrangian point  L4 of Dione.
Helene has dimensions of 43.4x38.2x26 km with a period of revolution of 2.736915 days. Planned flybys span the mission with close approaches on Nov 4, 2008, Mar 3, 2010 and Jun 18, 2011.
See 
Small Satellites Events (
xlsx, 
txt) observing log including range, flyby velocity and phase
For observation times and instruments compare Small Satellites Events file with
Master Schedule.
  
Observations were made by:
CIRS - Composite Infrared Spectrometer
ISS - Imaging Science Subsystem
UVIS -  Ultraviolet Imaging Spectrograph
VIMS - Visual and Infrared Mapping Spectrometer