McDonald Observatory Lunar Laser Ranging: Beginning the 
Second 25 Years


Authors:
P. J. Shelus,  R. L. Ricklefs, J. G. Ries, A. L. Whipple, and 
J. R. Wiant


Presenter:
P. J. Shelus


Laser ranging observations at McDonald Observatory have 
experienced remarkable success in both lunar and artificial 
satellite modes during its many years of operation.  Both 
instrumentally and operationally they have evolved with time, 
taking advantage of technological advances of all sorts.  
This has been culminated in the present incarnation of the 
McDonald Laser Ranging Station, the MLRS.  In spite of its 
relatively small receive aperture, as opposed to the earlier 
2.7-m system, we have attained quite an acceptable data 
volume, together with much better accuracy and precision.  We 
are just completing a multi-year up-grade that has 
concentrated on the lunar aspects of our total operation.  
Lunar data volume in 1993 and 1994 is almost triple that 
obtained in 1992; the number of UT0 Earth rotation points has 
increased by more than a factor five; and, for the first time 
since 2.7-m lunar operations in the mid-1980's, we are 
obtaining multi-corner data, i.e., ranges to more than one 
lunar surface retroreflector during a single observing 
session.  The progress has continued into 1995.  This paper 
describes this recent upgrade and summarizes its effects on 
the lunar data quality and quantity.