A sample standard calling sequence for reading the observing log data files
for all instruments for a 12-hour period starting at 00:00 on 8-May-92 is:
IDL> rd_obs, '8-may-92', '8-may-92 12:00', bcs, sxtf, sxtp, w_h, fid
An example for reading only SXT full frame entries is:
IDL> rd_obs, '1-jan-92', '1-jan-93', bcs, sxtf, /nobcs
Be aware that these datasets can get quite large so the time spans should probably
not exceed 10 days unless you are only accessing SXT full frame entries. See the
Reference Guide and the documentation header for RD_OBS for more details.