Title:  Herschel Space observatory and ground based observations of transneptunian Objects 
and Centaurs

Authors: R. Duffard, T. Mueller,  J.L. Ortiz, P. Santos-Sanz and the TNO's are Cool! team.

“TNOs are cool” was a Herschel Space observatory key Project granted with more than 370 
hours whose main goal was determining sizes and albedos of a large sample of more than 100 
trans-neptunian objects (TNOs). The interpretation of the Herschel thermal measurements 
requires accurate knowledge of absolute magnitudes and other parameters for the TNOs. That 
information has to be determined using ground based observatories. Also, for the initial planning 
and target selection, high accuracy astrometry for many of the targets was obtained to 
guarantee the correct pointing of Herschel to within the required specifications. Here we 
describe the combined efforts from Herschel and from the ground that have led to a considerable 
success. We will also describe the improvements we plan to do in the future to gain an even 
better knowledge of the physical properties of the TNOs.