  We report our measurements of the absolute transition frequencies of 5P_3/2,F
= 3 to nS and nD Rydberg states of 87Rb with high principal quantum numbers in
a wide range of values (n = 45-124). The measurements were performed using
Rydberg Electromagnetically Induced Transparency (EIT) in ladder-type
three-level systems. We measure the transition frequencies with an accuracy of
less than 2 MHz. We determine the values of the Rydberg-Ritz parameter for 87Rb
from our experimental measurements of the transition frequencies. Our
measurements of the absolute transition frequencies of the highly excited
Rydberg states would be useful for diverse applications in quantum information
processing, quantum simulation and quantum sensing with Rydberg atoms.
