1. Source flux accuracy from BLC analysis A. Strong MPE June 2002

2. Evaluation of absolute flux determination accuracy BLC long-distance runs ISDC system spiros 3.3 IRFs from GSFC (old: isdc `7', new `11') singles+multiples various source angles compared to new beam monitor fluxes Details: http://www.mpe.mpg.de/~aws

3. 60 Co 1173 keV angle=0 run 31 previous result (Dec 2001): fluxes too low by factor ~0.74 Several factors in same direction now improve this: old IRF new IRF 1170-1180 keV 1.555 1.704 1163-1183 keV 1.612 1.769 so extending energy range and new IRF gives 13.7% increase 13.7% increase Following corrections were not done before: correction for monitor (mask)-camera 1.71 m = 2.7% correction for divergence of beam ~ 2.7% New beam monitor analysis (David Attie): ~10% so combined factors increase factor from 0.74 to 0.97 i.e. Improvement, better consistency than expected from GSFC photopeak efficiency results from Dec 2001 meeting.

4. 60 Co 1173 keV 1163-1183 keV run angle spiros/monitor 31 0.0 0.965 35 0.5 0.973 36 1.0 0.981 41 10.0 0.980 1332 keV 1322-1342 keV 31 0.0 0.917 41 10.0 0.935

5. 241 Am 59 keV effect of IRF: 58-62 keV run angle spiros flux 134 0 0.350 old IRF 0.3665 new IRF angular dependence: 55-63 keV new IRF run angle spiros/monitor 134 0 0.902 144 -2 0.919 145 -6 0.596(?) 146 -8 0.847 147 -12 0.828 Low fluxes, consistent with GSFC photopeak efficiencies from Dec 2001 meeting

6. 137 Cs 662 keV Run angle spiros flux monitor spiros/monitor (a) (b) 65 0 1.541 1.8+-.07 0.88 0.90 a= with monitor mask-camera distance factor 1.0274 b= with also spiros beam divergence factor 1.0274 659-665 keV

7. 24 Na 2754 keV spiros fluxes: Day 10 Day 11 2700-2800 keV run angle spiros monitor spiros/monitor (a) (b) 327 0 0.629 0.58+-0.11 1.11 1.15 a= with monitor mask-camera distance factor 1.0274 b= with also spiros beam divergence factor 1.0274