1. © Imperial College LondonPage 1 GERB Straylight Characterisation 28th August 2003 GIST 19, RAL J A Hanafin

2. © Imperial College LondonPage 2 Feb 7-10 2003

3. © Imperial College LondonPage 3 29/4/03-9/5/03

4. © Imperial College LondonPage 4 7/8/03-14/8/03

5. © Imperial College LondonPage 5

6. © Imperial College LondonPage 6

7. © Imperial College LondonPage 7 Sw-tot subtraction Deep space data

8. © Imperial College LondonPage 8 Peak radiance v. relative solar declination Feb Aug/Apr

9. © Imperial College LondonPage 9 Summary of characterisation possibility Spatial pattern of feature is constant across GERB image and between channels Magnitude increases rapidly as relative solar declination < 18deg, and asymptotes to ~120Wm -2 sr - 1 at declinations < 16deg Spatial pattern shows reasonable symmetry with relative solar declination Spatial extent and magnitude changes with solar hemisphere Characterisation of feature is possible using SW channel at night

10. © Imperial College LondonPage 10 Further characterisation? Will require effort –Characterising –Implementing any solution in processing Data during these periods will always be compromised to some extent Data loss is currently 2hours/day around local midnight for ~15 days before and after eclipse season Extends eclipse season from 4months/year to 6months/year