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Purpose: To create a valid times file containing a modified set of accepted-time intervals. The program includes both a selection on master veto rate to eliminate times of anomalously high particle background rates (as per the suggestion in Snowden et al. 1992 and Plucinsky et al. 1993) and a time delay at the start of observation intervals, if necessary.
File Input:
1) Observation data set fits files - xxx_EVENTRATES.FITS and
xxx_EVENTS.FITS for German and US data or xxx_ANC.FITS and
xxx_BAS.FITS for RDF data.
2) Other fixed input - German data also requires an ascii file
ACTIME_FUL.DAT which lists as ordered pairs the start and stop times of
SASS accepted time intervals. These times can be extracted from the
xxx_EVENTS.FITS fits header under the HISTORY 'TIM_SEL' keyword.
Interactive Input:
1) Observation control - the eight or fewer character string listed above
as xxx.
2) Data format control - 1 for German data, 2 for US data,
3 for RDF data.
3) Time delay - for data processed early in the mission, occasionally
insufficient time was allowed before the accepted time interval began for
the detector high voltage to achieve its nominal level. This input creates
a time delay from the onset of detected events to reduce the effect of
spurious excursions. 15 seconds is a reasonable value for this parameter.
4) Master Veto threshold - upper limit on the allowed range of the master
veto rate. The program averages the master veto rate over 30-second
intervals. The most conservative value required is 
170 counts s 
.
Experience has shown that a selection of 220 counts s causes no
noticeable reduction in the quality of the data.
Ascii Output:
1) valid_times_all.dat - contains the accepted time intervals
for the observation with the input constraints. It consists of
ordered triplets of an interval counter, start time, and stop time.