© Imperial College LondonPage 1 Operations Report/ Operational Calibration Strategy GIST 19, RAL 28th August 2003 J A Hanafin

© Imperial College LondonPage 2 Operations Report Eclipse season operations Operations to date Instrument investigations Calibration modes Calibration strategy for duration of mission Operations home page

© Imperial College LondonPage 3 Eclipse season – autumn 2003 MSG software patch not ready yet Real-time full SEVIRI data not available yet => GERB will spend 2003 Autumnal eclipse season in SUNBLOCK –in-flight performance of instrument to date shows this is a safe strategy –allows monitoring of despin mirror performance and other housekeeping parameters

© Imperial College LondonPage 4 Instrument tests to date (2003) TCF step test: –results of first attempt inconclusive, to be repeated Mirror face offset test: –Successful, mirror sides largely corrected for non- parallelism, may need slight tweaking Sun avoidance test: –first attempt failed, for reasons TBD. To be repeated

© Imperial College LondonPage 5 Instrument calibration modes Alpha values test Integrating sphere mode Deep space mode PSF mode Lunar mode

© Imperial College LondonPage 6 Alpha values Initial test completed 14/7/03 Results awaiting analysis before completion of test Not time-specific, can be timed to avoid aliasing Repetition of test TBD

© Imperial College LondonPage 7 Shortwave calibration Previous broadband radiation missions have shown quartz filter degradation Current series is not optimal in terms of absolute radiance, but is very close Second series could be initiated, but would involve twice the normal mode data loss, back-to-back with the current series …Inevitable aliasing problem Alternative: scans twice a year at equinox

© Imperial College LondonPage 8 Deep space mode Characterisation of in-flight instrument performance BB temperatures were varied during these measurements to determine temperature dependence of gains Current deep space and blackbody straylight issues may require rethinking of gain calculation

© Imperial College LondonPage 9 Deep space mode Doesn’t compromise data collection, but reduces temporal resolution by 2 (could be improved with a shorter space scan) Recommendation: –A full year of limited deep space data characterise instrument cycles characterise straylight Both useful data for future instruments

© Imperial College LondonPage 10 PSF mode Data to date covers in-flight characterisation, pending analysis Disruption to data collection depends on PSF mode and ability to process PSF data as normal May be useful to repeat on an annual basis in case of optics distortion 500 scanlines

© Imperial College LondonPage 11 Lunar scans 4 scans to date (Jan, May, Aug) Potential to acquire lunar data most months Lunar data of scientific interest as well as for calibration data ROLO (RObotic Lunar Observatory, USGS) are interested in collaboration, providing they can support non-NASA instruments May be useful for long term data series Analysis for absolute calibration will require significant effort The more data there is, the more useful it will become

© Imperial College LondonPage 12 Operational Strategy: calibration tests v. NORMAL data collection TestDurationFrequencyDisruption to NORMAL mode Alpha1 hourAnnualYes Deep space TBD No, but reduces frequency SW Cal45 minQuarterlyYes Lunar45 minTBD (Monthly?) Yes PSFTBDTBD (Annual?) Depends on scan type/data processing

© Imperial College LondonPage 13 GERB Operations home page GIST information –Agenda –Minutes –Presentations GERB data ‘previews’ Links –Data access – GGSPS/ROLSS –Project links –Contacts Secure area access….

© Imperial College LondonPage 14 GERB Operations home page Secure area – GIST-only access (please!) –Username: gerbteam –Password (case sensitive): POLARIS Data quality information –Newsletter –Anomaly reports ‘Support team’ meeting information –Minutes/reports from low level working groups –GGSPS –Operations –Data quality Operations information –Summary of GERB operations (indication of availability of NORMAL mode data) –GERB operational database (calibration mode times, SEVIRI/MSG operations, including earth sensor unit swaps, details of cailbration modes)