Using two telescopes of beam-beam counters, CDF (Collider
Detector at Fermilab) has measured the luminosity to an accuracy of 4.1%
(3.6%) in run Ib(Ia). For run Ib (Ia) the average luminosity was 9.1(3.3) x
1030 cm-2 sec-1. For a typical data set the integrated luminosity was
86.47 (19.65) pb-1 in run Ib (Ia) resulting in a total integrated
luminosity of 106.1 +/- 4.1 pb1. This paper shows how we have determined
the accuracy of our results.