When a geosynchronous Earth satellite is launched, why is there a launch window?

wow a lot of wrong answers here

a launch window is about getting the package up there WITHOUT hitting other satellites

some satellite orbits take them over the whole planet over time, a rocket has to be timed not to hit those

and it's for every launch, not just 1 type

Because the need to open it ha ha

No

It takes perfect timing to get it up to syncronisity with the Erarth's spin never mind just orbiting

Your am/pm scenario would equate to an 180 degree placement difference in placement

If you put it up in the daytime, it could hit the Sun.

The geosychronous satellite does not go straight up to its spot. It is launched first to an elliptical orbit with perigree at low earth orbit, and a high apogee, then boosted to its spot with three burns a bit later. Planes helicopters and balloons have to be prevented from flying into the path of the rocket at launch, and the rocket has to be prevented from being launched into the path of planes, helicopters and balloons. This is called a launch window.

Because there is still the matter of WHERE above Earth you want it to be in stationary orbit. It will take a lot more fuel to make it end up above America, or Africa, or the middle of the Pacific, or wherever you want it to be if you launch it at the wrong time.

"Is't it the same travel time to get to their spot? If I drive from New York to Chicago, it's the same distance if no matter when I leave." That is not the same thing at all. You're moving with the Earth so you can treat it as stationary. But once you get off the Earth, it's moving underneath you so the time you start matters.

They still have to get out of the earth's gravitational pull. And through the mesosphere

Depends on who’s launching it. From Kennedy space center, you can only clear the air lanes and ocean area for so many hours.

It doesn't wind up in the same place. Geosynchronous satellites are spaced out around the globe -- meaning that they need it to wind up in a specific spot. Hence, the launch window tells them the optimum time for placement. (They want to use the least amount of fuel to get it in position so that they have a reserve for adjusting and maintaining the location.)

Some how the term "door" just did not work.

There is/are a lot of calculations that have to be made and things to take into account- such as space junk! If it can be avoided no one wants to loose a brand new satellite because it collided with a piece of junk from sputnik 12 or the like.