turtlesim initialises at x=[inf], y=[inf], theta=[0.000000]

edit

When I execute

~$ rosrun turtlesim turtlesim_node

an empty blue "TurtleSim" simulation window pops up and the following messages are issued:

$ rosrun turtlesim turtlesim_node
QGtkStyle was unable to detect the current GTK+ theme.
[ INFO] [1335558676.993640551]: Starting turtlesim with node name /turtlesim
[ INFO] [1335558677.369623672]: Spawning turtle [turtle1] at x=[inf], y=[inf], theta=[0.000000]

Question 1 (of 2): Why is turtle1 spawned at a location beyond the end of the universe, instead of at its origin [0,0] ?

I executed

~$ rosrun turtlesim turtle_teleop_key

to see if the [x,y] coordinates would change when the up/down arrow keys were pressed, but unfortunately this is not the case. The [theta] value however -does- respond when the left/right arrow keys are pressed.

Output of the /turtle1/command_velocity topic:

$ rostopic echo /turtle1/command_velocity
linear: 2.0
angular: 0.0
---
linear: -2.0
angular: 0.0
---
linear: 0.0
angular: 2.0
---
...

Output of the /turtle1/pose topic:

...
---
x: inf
y: nan
theta: -3.06081461906
linear_velocity: 0.0
angular_velocity: 2.0
---
x: inf
y: nan
theta: -3.02881479263
linear_velocity: 0.0
angular_velocity: 2.0
---
x: inf
y: nan
theta: -2.99681472778
linear_velocity: 0.0
angular_velocity: 2.0
---
...

Question 2 (of 2): Is there perhaps a way to hard-set the [x,y] location ? E.g. something in the line of a command like "set turtle_pos=[0,0]" ?