Here are the rules...
Go to the above coords at 4:46, if you are late don't bother going, Either day or night will do ok, Stand at the coordinates for FOUR minutes and then look SOUTH and you will have the CLUE for your final step in the cache.
42* 08.461
121*49.CLUE
Window of opportunity? You bet, but it is short.
Have fun and guess what NO CLUES NO HINTS NO HELP WHATSOEVER :) Sorry all this one just doesn't need it if you go when you are supposed to.