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Analysis of the Astrium radiation 2 nd campaign RVS data. C. Allende Prieto MSSL, Univ. College London. The setup. Red enhanced TDI-operated e2v CCD: calibration runs with un-irradiated CCD, rest with partly irradiated (2e9 p+/cm 2 ) CCD
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Analysis of the Astrium radiation 2nd campaign RVS data C. Allende Prieto MSSL, Univ. College London
The setup • Red enhanced TDI-operated e2v CCD: calibration runs with un-irradiated CCD, rest with partly irradiated (2e9 p+/cm2) CCD • Mask and optics mounted on a movable train displaced in sync with TDI charge shift • CCD read for 8000 TDI periods, runs separated by 27s • Runs with different illumination levels and detector temperatures
What we get • Samples: signal over 9 pixels in AC • Sample 1: pre-scan • Samples 2-3-4: reference square • Samples 5-13: non-irradiated area • Samples 14-32: irradiated area • Data for V6.10, V6.00, V5.76, V5.52, V5.28, V5.21 • Data for T=161, 175, 185, 195 K
Calibration • Background • flatfielding
Signal levels • V6.00= 300 e- (Grvs~ 7.7) 4 runs • V5.76= 30 e- (10.2) 5 • V5.52= 3 e- (12.8) 10 • V5.28= 0.5 e- (15.7) 50 • V5.21= 0.3 e- (16.9) 100 WARNING: Spectra look much better than they will do for a single transit
CTI effects • Distorted continuum shape, especially at the beginning • Net loss of charge, trailing charges • Filling-in of the absorption lines, hence reduced equivalent widths • Distorted line shapes, systematic shifts of the line centers • Reduced line-to-continuum contrast, hence larger random errors in RV
Quantitative analysis (185 K) Grvs net loss RV bias EW change _______________________________ 7.7 4% -0.3 pix - 5% 10.2 16% -0.9 pix -30% 12.8 28% -1.3 pix -60% 15.7 44% -1.4 pix -70% 16.9 44% -1.5 pix -80%
Damages • Modest effects regarding RV bias: less than 2 pixels or 20 km/s at the lowest illumination levels • Modest charge loss: < 50% at worse • But dramatic EW reduction: 80% at 185 K, 100% at 195 K for Grvs~ 16.9 • The lines are washed down, causing a huge impact on the random errors on the derived RVs: x20 at Grvs~ 15.7 mag (400 km/s), x7 at Grvs~ 12.8 mag (35 km/s) • Losing 4 magnitudes?