upperlimits plot question

I am making some plots using the upperlimit keyword in the errorbar command as in the examples.
The arrows are drawn correctly but I notice that the exact limit point is in the middle of the arrow and not where the arrow starts.
Is it any way to improve it and have the beginning of the arrow represent the actual limit measure?
Also is there any way to increase the thickness of the arrow?




Antonino Cucchiara
PhD candidate
Department of Astronomy&Astrophysics
Penn State University
website: www.astro.psu.edu/~cucchiara/