IRAS Explanatory Supplement
VI. Flux Reconstruction and Calibration
C. Absolute Calibration
C.2 Point Source Calibration
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The point source amplitudes used to determine the absolute calibration of the IRAS bands were all measured using the pointed observation rode, rather than using the results of the survey per se. These pointed mode measurements have less intrinsic scatter than measurements obtained during the survey since the cross-scan position of a source with respect to individual detectors is well defined and flashes of the internal reference source were taken at the same time as the calibration source measurement. Each source was crossed at least five times on at least two separate occasions. In addition the reductions of the pointed observations were available before the survey processing was completed. Table VI.C.1 shows, however, that statistically the results of the survey reductions and pointed observations agree. The three piece fit to the feedback resistor curve shown in Figure VI.A.1 was assured throughout. Except for this the system was assured to be linear.
Table VI.C.1
Band
12 µm
25 µm
60 µm
100 µm
Star
mag1
dif2
mag
dif
mag
dif
mag
dif
Tau-3.08
-0.08
-3.02
-0.05
-3.03
-0.08
-2.81
-0.02
Aur-1.90
-10.01
-1.95
-0.03
-1.85
+0.01
-1.85
-0.06
CMa-1.36
-0.00
-1.38
-0.06
-1.23
+0.04
-
-
CMi-0.71
+0.03
-0.72
+0.00
-0.72
-0.02
-
-
Gem-1.21
-0.01
-1.19
-0.02
-1.22
-0.05
-1.19
+0.19
Leo+1.58
-0.08
+1.63
-0.09
-
-
-
-
UMa+2.39
+0.01
+2.33
+0.03
-
-
-
-
UMa+1.99
-0.00
+1.93
-0.09
-
-
-
-
Boo-3.22
-0.07
-3.09
+0.01
-3.02
+0.09
-3.02
+0.21
Dra-1.44
-0.01
-1.50
-0.03
-1.42
+0.06
-1.48
+0.07
Lyr-0.02
-0.03
-0.17
+0.01
-1.94
+0.01
-3.00
+0.12
Gru-3.40
+0.02
-3.50
-0.05
-3.52
-0.02
-3.48
+0.19
Avg
-0.019
-0.030
+0.005
+0.10
Sigma3
0.036
0.040
0.053
0.11
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