This directory contains ORPA sweep data (RDR's) for orbits 3900 - 3999.
Data are organized into single orbit files which follow the naming convention
ORBxxxx, where xxxx is a four digit orbit number. In addition, for each data 
file there is a label file which describes the file characteristics, such as 
number of records, record length, etc. called ORBxxxx.LBL. The format for the
data files is described in DATAFMT.TXT.   

Additionally, the files RDR_DATA.IDX and SWEEP.IDX contain indexed information 
for each orbit and for each sweep, respectively. Each file has a corresponding
".LBL" file which describes the file characteristics and format.