Addons i use to track Eclipse are Squawk&Awe and also Tell Me When.
Curse dont have it so couldn't give you a link but WoW Matrix has the addon.
This is a link to my UI to show you what it looks like.
http://i331.photobucket.com/albums/l...710_192412.jpg
Its very simple to use and set up also, simply enter the spell ID of what you want, in this case Eclipse and if you want both Solar and Lunar on the same box as i do you can simply enter "45817 ; 45818" into the spell id box.
Simply enable the icon >> Select it to "Buff" and then simple /tmw to close the options.
Its also good to track everything else, i use it for trinkets, owlkin frenzy, cloak enchant, ashen verdict ring proc etc. I advise you get it, helps alot!!!!
Need any more help on setting it up feel free to PM me or post back on here.
http://eu.wowarmory.com/character-sh...n=Kaskad%C3%A9