Kipp&Zonen Brewer MkIII - Manual (Page 106)

MKIII OPERATOR’S MANUAL 103
Method:
Type SL. The test runs through the same temperature and foreoptic positioning procedures
described in HG, then waits the obligatory five minutes for the quartz-halogen lamp to warm up.
The program then conducts seven measurement runs over the dark-count channel and the five
operational wavelength channels. Each run cycles the slitmask through 20 oscillations,
accumulating the photon counts in the BASIC one-dimensional F() array (described under
Preliminary Data Reduction). These raw counts are printed in the following format:
Brewer Temp = 27 C ( 3.56 V)
C.U.T. CY ZEN MU DRK 1 2 3 4 5
SL0 20:54:25 20 65.63 2.384 32 1102112 1052861 1066768 956627 820941
SL0 20:55:02 20 65.67 2.388 35 1101966 1054190 1067478 957870 821186
SL0 20:55:40 20 65.72 2.392 43 1102630 1053024 1067318 958662 821366
SL0 20:56:18 20 65.76 2.395 36 1101330 1054009 1068002 957890 821567
SL0 20:57:02 20 65.81 2.4 31 1101960 1053736 1068197 957257 820730
SL0 20:57:46 20 65.86 2.404 37 1102690 1052931 1067378 959002 821232
SL0 20:58:24 20 65.9 2.408 43 1102507 1053022 1067047 958135 822097
The SL0 indicates that the Standard Lamp test was performed with Filter Wheel #2 in position 0 (ie
no neutral-density attenuation). CY is the number of slit-mask oscillations over which the counts
were accumulated. ZEN and MU are the current solar-zenith angle and airmass respectively (these
are irrelevant to the SL test and are presented for operator information only). The next six columns
are the photon count totals for the dark channel and the five operational channels. When all seven
measurement runs are complete the program corrects the raw photon counts for dark count,
deadtime, and temperature-dependence, then prints a series of summary statistics:
20:56:22 Feb 21/85 65.763 2.395 27 C DEG SL 0
Mean1 mean5 MS(4) MS(5) MS(6) MS(7) MS(8) MS(9)
1102170 821302 -623 -426 -488 -694 596 418
+ 483 + 445 + 3 + 5 + 5 + 4 + 15 + 9
The first line shows the time, date, solar-zenith angle, airmass, instrument temperature and test
identification. The second line of data displays the mean corrected count for channels 1 and 5, the
single-ratios MS(4) through MS(7), and the double-ratios MS(8) (the SO
2
ratio), and MS(9) (the O
3
ratio). The derivation and interpretation of these values is detailed under Preliminary Data
Reduction.
The third line of data shows the standard deviation for each of the quantities in the line above
(there is no ASCII symbol for '±', hence the leading '+' sign).
The single-ratios MS(4) through MS(7) should remain reasonably constant from test to test; the
allowable drifts in the SO
2
(MS(8)) and O
3
(MS(9)) double-ratios are about ±1.5%.
THERMAL TESTS
The Thermal Tests consist of a battery of diagnostics which determine the extent to which the
spectrophotometer's performance is affected by temperature.
Measurements are made with the quartz-halogen (standard) lamp. Light intensity measurements
are taken at a number of points which span the temperature range -10 to +40 °C. The wavelength
setting must be recalibrated (via the HG command) at each new temperature before the standard-
lamp intensities are measured. These intensity data are analyzed to yield the absolute temperature
coefficients for each of the five operational wavelengths; the negative of each coefficient is stored
in the instrument Constants File for subsequent use during data reduction.
During the course of the Thermal Tests all of the Brewer electromechanical subsystems should be
thoroughly exercised, and any malfunction corrected.
The PRFILE.BAT program is used to process the data and determine the temperature coefficients
for the brewer.