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Laboratory for Atmospheric and Space Physics

SORCE TIM Data Products Release Notes

TIM Version 16 (29 May 2014):

  • Calibration adjustments (aperture diffraction, temperature coefficients of certain resistances and reference voltages) lead to ~25 ppm upward shift in level 3 TSI
  • Further improvements to instrument degradation model, time-dependent uncertainty model
  • New data added from the SORCE hybrid mode starting in March 2014
  • Science processing codebase now mission-agnostic, supports SORCE, TCTE, and (future) TSIS missions
  • Improvements to half-cycle and feed-forward telemetry processing accept more good data points
  • Many more unit tests for science processing codebase

Previous Notes:

TIM Version 15 (27 January 2014):

  • Mean thermistor temperatures computed across the cavity filter interval replace raw temperatures in many calculations
  • Stricter temperature limits for some instrument components reject poor quality irradiances
  • Truncation error that affected DN linearity corrections fixed
  • New instrument degradation model utilizes actual exposure times instead of mission days
  • Time-dependent uncertainties assigned to the level 3 TSI
  • New data added from the SORCE campaign mode in December 2013

TIM Version 14 (2 July 2013):

  • Interpolated telemetry over gaps of 1 or 2 seconds
  • Heater saturation and cone_bc_temp fixes
  • DN Filter quality flag fix (first introduced as a V13 patch)
  • Updated degradation corrections
  • Updated gain calibrations
  • Updated dark model

TIM Version 13 (11 July 2012):

  • Updated degradation corrections
  • Updated gain calibrations
  • Updated dark model

TIM Version 12 (21 November 2011):

  • Updated degradation corrections
  • Updated gain calibrations
  • Updated dark model

TIM Version 11 (9 December 2010):

  • Improved (and updated) dark irradiance algorithm and model (more accurately models the dark irradiance correction)
  • Updated degradation corrections using improved dark models for all cavities
  • Updated gain calibrations

TIM Version 10 (8 December 2009):

  • Updated degradation estimates based on latest measurements, including improvements to selection of dark data
  • Updated gain calibrations based on latest measurements
  • Updated dark model based on latest measurements
  • Corrected ShutterWaveform for less than 1 ppm error in algorithm
  • Corrected 3 ppm error in Sun-Earth distance values prior to 1 Dec. 2008

TIM Version 9 (8 December 2008):

  • Updated degradation calibration
  • Updated dark calibration
  • Updated servo gain calibration
  • Using new SunDotEarthDotMoon, in addition to fsdotmoon, to detect solar eclipses
  • Fixed ephemeris apparent distance (3 ppm)
  • Doppler 1-v/c correction changed to (1-v/c)^2 (25 ppm)

TIM Version 8 (28 November 2007):

  • Updated equivalence ratio calibration
  • Updated degradation calibration
  • Updated exponential dark irradiance model calibration
  • Updated servo gain calibration
  • Updated temperature calibration of servo gain
  • Changes to support production of dark irradiances for all four cones
  • Changed maximum allowable temperature from 45 to 50, to accord with Ops’ yellow (red?) value. (Temps often in this range.)
  • New intermediate 1AU corrected irradiance product (to facilitate degradation anaylsis)
  • Earth-to-Sun doppler correction now is retracted from true Earth distance irradiance product (just as Earth-to-Sun 1/r^2 distance correction, which has always been retracted).

TIM Version 7 (6 July 2006):

  • Updated TIM degradation calibration data (through April, 2006)
  • Updated TIM servo gain calibration data (through April, 2006)
  • The existing TimDarkIrradianceData database table has been renamed to TimSvdModelDarkIrradiance. The renamed table contains all the previous versions of dark irradiance data, as well as new irradiance data generated using the SVD algorithm.
  • A second table for dark irradiances, “TimExpModelDarkIrradiances” has been added. This second table will contain only new irradiance data created with the EXP algorithm and based on a fit to the SVD coefficients.
  • Both sets of dark irradiance data will be generated daily.
  • Interpolation-based Solar Distance and Doppler corrections:
    • With version 7, SolarDistanceAndDoppler data are stored in the database at a fixed cadence of 60 seconds. SolarDistanceAndDoppler values for specific timetags are interpolated from this cadenced data using LaGrange Interpolation, rather than calculated directly as in the past.
    • A new database table, “SolarDistAndDopplerFixedStep” supersedes the existing “SolarDistanceAndDoppler” database table. The new table will contain only the fixed cadence data. All the previous versions of SolarDistanceAndDoppler data will be kept in the existing “SolarDistanceAndDoppler” table. Only the fixed cadence data will be generated in the nightly processing.
    • A new IDL procedure, tabulated_solar_distance_and_doppler.pro, is available. This procedure computes SolarDistanceAndDoppler from the fixed-cadence data. This procedure can compute values for one or more specific timetags or a mission day.
  • An additional quality flag has been added. The new quality flag indicates that the nearest telemetry datum used to was older than 30 seconds. This flag is set in the PhaseDetectedDataNumbers and the level 3 data. This flag is the binary bit 2^15 in the qualityFlags field.
  • An additional field has been added to data in preparation for “quick look” processing. A “provisional data” flag has been added, indicating the data were computed without all calibration data being available, i.e. the data are provisional and temporary. The data will be replaced by permanent data when all the calibration data are available.

TIM Version 6 (12 December 2005):

  • Updated degradation calibration data (through 10/2005, ~ 10 ppm effect on recent data relative to Revision 5)
  • Updated servo gain calibration data (through 10/2005)
  • Added additional quality checks to the data used in creating dark irradiance models
  • Expanded and improved the uncertainty estimates in the data which are:
    • Instrument Uncertainty (~350 ppm) – instrument absolute accuracy
    • Instrument Precision (5 ppm) – sensitivity to signal change (noise)
    • Solar Standard Deviation – standard deviation of the Level 2 data averaged to produce Level 3
    • Measurement Uncertainty – RSS of Instrument Uncertainty and Solar Standard Deviation
  • A new data format with additional columns for new reported uncertainties in ascii data files (as described above)
  • Added a “provisional data” flag indicating whether the data are provisional or final (for future use)

TIM Version 5 (9 June 2005):

  • Updated servo gain calibration data
  • Updated degradation calibration data
  • Smoother propagation of SORCE orbital ephemerides
  • Improved interpolation of servo gain data
  • Updated data versioning software

TIM Version 4 (16 September 2004):

  • Updated Linearity Correction. Takes into account recent measurements of linearity in the two TIM “witness” instruments, providing much better accuracy in the linearity correction, and reduces annual trends in the TIM TSI data to a few ppm (~100 ppm effect overall).
  • Updated Dark Correction Algorithm to generate dark data with the same convolution filter that is used in the phase sensitive detection algorithm that produces the primary TSI irradiances.
  • Updated servo gain calibration to include ongoing in-flight characterization measurements.
  • Updated cone degradation correction.
  • Filter for data spikes due to occasional telemetry errors.
  • Minor bug fixes and performance improvements.

TIM Version 3 (7 July 2004):

  • Updated aperture calibration data with an improved scattering correction (~20 ppm effect)
  • Added additional verification of the shutter waveform consistency prior to computation of phase detected data numbers. This eliminates anomalous data values that were being produced occasionally.

TIM Version 2 (7 May 2004):

  • Addition of an instrument degradation correction (~60ppm in the primary TIM cone)
  • Updated Servo Gain Calibration data, including recent in-flight servo gain calibration measurements, and the correction of a small error in the previous calibration data that resulted in a small (<5 ppm) error being introduced into the TSI irradiance data.
  • Updated heater circuit trace resistance calibration data, incorporating improvements to the resistances measured during instrument characterization and the Copper temperature coefficient.
  • Use of linear interpolation of instrument thermistor data rather than bspline thermistor models. The bspline models were not able to adequately represent the thermistor data when sharp changes in the derivative occur. Use of linear interpolation more accurately models these local extrema.
  • An “exclude time block” was inserted to mask three orbits of data on December 4, 2003 which are presumed invalid. The cause of the anomalous data is still under investigation.
  • Correction of a small bug in the code that generates a shutter waveform during instrument in-flight servo gain calibration experiments. This bug caused small errors in the shutter waveform and was complicating the analysis of in-flight gain measurements.
  • Numerous other minor improvements and bug fixes.

TIM Version 1 (24 October 2003):

  • Dark correction algorithm which accounts for instrument day/night thermal differences.
  • Applied ESR power linearity correction.