Straylight Values
From Tauwiki
The table below gives counts over the detector/sec from direct sunlight. The angle means that between direct incoming sunlight and FOV direction.
The expression used is,
Counts = Sun_ct * PST
where Sun_ct = 10^15. The cps that would fall over detector due to the direct sunlight through BBF filter.
Angle BBF SF1 SF2 SF3 NBF
30.0 1.250e+07 11251.1 357143 1.40766e+06 107759.0 31.0 1.130e+07 10177.3 323057 1.27331e+06 97474.1 32.0 1.011e+07 9103.51 288971 1.13896e+06 87189.7 33.0 8.921e+06 8029.7 254886 1.00462e+06 76905.2 34.0 7.728e+06 6955.9 220800 870270 66620.7 35.0 6.535e+06 5882.09 186714 735923 56336.2 36.0 5.342e+06 4808.28 152629 601577 46051.7 37.0 4.149e+06 3734.47 118543 467230 35767.2 38.0 2.956e+06 2660.67 84457.1 332883 25482.8 39.0 1.763e+06 1586.86 50371.4 198536 15198.3 40.0 570000 513.051 16285.7 64189.2 4913.79 41.0 528000 475.248 15085.7 59459.5 4551.72 42.0 486000 437.444 13885.7 54729.7 4189.66 43.0 444000 399.64 12685.7 50000.0 3827.59 44.0 402000 361.836 11485.7 45270.3 3465.52 45.0 360000 324.032 10285.7 40540.5 3103.45 46.0 328000 295.23 9371.43 36936.9 2827.59 47.0 296000 266.427 8457.14 33333.3 2551.72 48.0 264000 237.624 7542.86 29729.7 2275.86 49.0 232000 208.821 6628.57 26126.1 2000.0 50.0 200000 180.018 5714.29 22522.5 1724.14 51.0 200000 180.018 5714.29 22522.5 1724.14 52.0 200000 180.018 5714.29 22522.5 1724.14 53.0 200000 180.018 5714.29 22522.5 1724.14 54.0 200000 180.018 5714.29 22522.5 1724.14 55.0 200000 180.018 5714.29 22522.5 1724.14 56.0 200000 180.018 5714.29 22522.5 1724.14 57.0 200000 180.018 5714.29 22522.5 1724.14 58.0 200000 180.018 5714.29 22522.5 1724.14 59.0 200000 180.018 5714.29 22522.5 1724.14 60.0 200000 180.018 5714.29 22522.5 1724.14 61.0 200000 180.018 5714.29 22522.5 1724.14 62.0 200000 180.018 5714.29 22522.5 1724.14 63.0 200000 180.018 5714.29 22522.5 1724.14 64.0 200000 180.018 5714.29 22522.5 1724.14 65.0 200000 180.018 5714.29 22522.5 1724.14 66.0 200000 180.018 5714.29 22522.5 1724.14 67.0 200000 180.018 5714.29 22522.5 1724.14 68.0 200000 180.018 5714.29 22522.5 1724.14 69.0 200000 180.018 5714.29 22522.5 1724.14 70.0 200000 180.018 5714.29 22522.5 1724.14 71.0 200000 180.018 5714.29 22522.5 1724.14 72.0 200000 180.018 5714.29 22522.5 1724.14 73.0 200000 180.018 5714.29 22522.5 1724.14 74.0 200000 180.018 5714.29 22522.5 1724.14 75.0 200000 180.018 5714.29 22522.5 1724.14 76.0 200000 180.018 5714.29 22522.5 1724.14 77.0 200000 180.018 5714.29 22522.5 1724.14 78.0 200000 180.018 5714.29 22522.5 1724.14 79.0 200000 180.018 5714.29 22522.5 1724.14 80.0 200000 180.018 5714.29 22522.5 1724.14 81.0 180000 162.016 5142.86 20270.3 1551.72 82.0 160000 144.014 4571.43 18018.0 1379.31 83.0 140000 126.013 4000.0 15765.8 1206.90 84.0 120000 108.011 3428.57 13513.5 1034.48 85.0 100000 90.009 2857.14 11261.3 862.06 86.0 80000 72.007 2285.71 9009.01 689.65 87.0 60000 54.005 1714.29 6756.76 517.24 88.0 40000 36.003 1142.86 4504.5 344.82 89.0 20000 18.001 571.42 2252.25 172.41 90.0 0 0 0 0 0
There are two cases when the sunlight <90 deg.
1. For higher DEC (>60) observations, from the geometry;
For 18 hrs - 1 hrs no contribution from scattered light, apart from a small number from Plasma thruster.
For 1 hrs - 15 hrs the scattered light will have contribution, which will be more than direct light due to the reflection from Solar Panel.
For 15 hrs -18 hrs both will contribute almost equally.
These ranges are for sunlight coming (angle < 90 deg) from the North / South side of GSAT. ie, for higher declination observations during Summer /Winter. That is while observing northern DEC during Summer and vice verse. In this case and for 18 hrs - 1 hrs, there will be no effect due to Solar Panel, and Engine parts.
2. But if the sunlight is reaching at angle <90 from East/West side (ie, during day times), for any season, the scattered light will be much more due the contribution from almost all the parts.
Conclusion
For 18 hrs - 1 hrs and for the observation towards high DEC (North in summer and South in Winter) the stray light will be almost same (only slightly different due to Plasma thruster reflection) as the calculated (and sent before two days) values.
