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

© Imperial College LondonPage 1

Calibration Commissioning Report GIST 19

RAL, 27th August 2003

GERB Instrument Team & Operations Team


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 16:23

0.0 step size Earth scan1/24/03 14:151/22/03 12:17

OperationEnd TimeStart Time


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


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


Alpha values test

Data acquired during initial test 14/7/03


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.



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


Deep space mode


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)


PSF scans

1400 scanlines 1800 scanlines500 scanlines


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


Static:2 tests completed

Motion tracking:1 test completed


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)

Documents

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