© Imperial College LondonPage 1 Calibration Commissioning Report GIST 19 RAL, 27th August 2003 GERB Instrument Team & Operations Team

© Imperial College LondonPage 2 GERB operations 1 year on… Sunblock during Sun Avoidance period 8/15/03 14:38 Lunar scan8/15/03 14:388/15/03 14:04 SW Calibration8/14/03 15:398/14/03 15:01 Lunar scan8/14/03 14:028/14/03 13:30 PSF - fine earth limb scan8/4/03 13:348/1/03 13:02 PSF - fine scan of African coastlines7/22/03 13:187/22/03 8:57 PSF - fine scan of African coastlines7/16/03 13:087/16/03 9:08 Alpha values test7/14/03 13:227/14/03 12:28 Deep Space scan7/11/03 16:097/9/03 8:09 Lunar scan5/14/03 11:535/14/03 9:48 SW Calibration4/30/03 15:334/30/03 14:53 Safe during Sun Avoidance period4/28/03 12:182/10/03 15:42 SW Calibration2/10/03 15:422/10/03 15:10 Deep Space scan2/6/03 9:452/3/03 16:05 PSF: 0.2 steps, whole Earth1/31/03 15:001/30/03 17:26 Lunar scan1/23/03 17:171/23/03 16: step size Earth scan1/24/03 14:151/22/03 12:17 Operation End TimeStart Time

© Imperial College LondonPage 3 Calibration Commissioning Tests Status Alpha values test –Initial test completed Integrating sphere mode –3 tests completed in current series –ongoing Deep space mode –2 tests completed to determine temperature dependence of gains –ongoing PSF mode –3 tests completed –ongoing Lunar mode –Lunar data acquired on 4 different dates –ongoing

© Imperial College LondonPage 4 Alpha values test Aim: to determine validity of alpha values used in signal processing Data acquired to date: –Initial test completed 14/7/03 – data acquired as GERB scanned between baffle and deep space Results to date: –Data awaiting analysis before completion of test –Alpha value analysis using BB heating and cooling data is underway

© Imperial College LondonPage 5 Alpha values test Data acquired during initial test 14/7/03

© Imperial College LondonPage 6 Integrating Sphere Aim: to monitor possible degradation in shortwave channel over mission lifetime Data acquired to date: –10/2/03 –30/4/03 –14/8/03 Results to date: –IS spatial homogeneity varies with solar hemisphere. –Test relies on thermal stability of sphere, which is constant, to first order.

© Imperial College LondonPage 7

© Imperial College LondonPage 8 Deep space mode Aim: to check gain stability Data acquired to date: –16h 3rd Feb - 10h 6th Feb 2003 –8h 9th July - 16h 11th July 2003 –BB temperatures were varied during these measurements to determine temperature dependence of gains Results to date: –IBB look up radiances improved –BB & midnight straylight detected –Diurnal/seasonal gain cycles identified

© Imperial College LondonPage 9 Deep space mode

© Imperial College LondonPage 10 PSF mode Aim: to determine in-flight E-W PSF Data acquired to date: –22 hours of full earth disk at 1/5 GERB resolution –4 hours of African coastlines at 1/18th GERB resolution on 2 different days –72 hours of earth limb at 1/28th GERB resolution, including 24 hours either side of an MSG sensor swap for Geolocation studies Results to date: –Data awaiting analysis (dependent on SEVIRI data availability)

© Imperial College LondonPage 11 PSF scans 1400 scanlines 1800 scanlines 500 scanlines

© Imperial College LondonPage 12 Lunar scans Aim: check on shortwave calibration and in-flight PSF Data acquired to date: –Static scans high resolution scan no compensation for moon’s motion between scanlines 3 scans, to west and east of earth, allowing greater pixel coverage –Motion tracking scans high resolution scan compensates for moon’s motion between scanlines timing constraints limit pixel coverage

© Imperial College LondonPage 13 Static: 2 tests completed Motion tracking: 1 test completed

© Imperial College LondonPage 14 Future activities Calibration commissioning nearing end Aim for data release: mid 2004 Analysis of calibration data acquired to date requires effort not available at IC –PSF (G. Robinson/other) –Alpha values (IC/Leicester U.) –Integrating sphere (RMIB/RAL) –Deep space (IC/RAL/other) –Lunar scans (IC/RAL/other)