The Jedi Temple on Coruscant was built over a Force Nexus, or a place that was particularly powerful in the Force. This one was marred with just the faintest hint of Dark Side contamination. This caused the Jedi on Coruscant to have a harder time getting accurate visions.of the future - they would often be indistinct, or even maliciously misleading. This greatly assisted Palpatine in hiding his dreadful might in the Dark Side from the Jedi during his time as Senator of Naboo and Supreme Chancellor.
But that's just how Palpatine got into place to kill the Jedi. Between casualties from the war, the attack on the Jedi Temple, and Order 66, an estimated 1 to 2% of the original 10,000 Jedi were left alive, and all of those survivors were recorded as members of the Order in the computer banks of the Jedi Temple, along with data on their travels and assignments during their time in as Jedi, as well as the location of most every location significant to the Jedi Order, from minor temples, artifact repositories, and all manner of other places the Jedi would want to keep track of.
Asides from Yoda, who was told where to find the Force Nexus on Dagobah by the ghost of Qui-Gon Jinn, who only knew about it from and Obiwan Kenobi, who hid on what might have been Darth Vader's least favorite planet in the entire galaxy, most survivors of Order 66 wouldn't have had anywhere they could actually go to hide.
Couldn't tell you how Qui-Gon Jinn found Dagobah, though. That's a mystery to me. :shrug: