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| = Level 1 HMI Data Products = | = Level 1+ HMI Data Products = HMI "Level-1" products are simply the individual filtergrams from level-0 but with flat-field images applied and fits to the limb computed to find the disk centerposition. Also ancillary metadata in included, such as SDO velocity and location from the SDO Flight Dynamics Service. |
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| Level 1 HMI Products are calibrated science measurements computed from corrected level 1 HMI filtergrams. | Level 1.5 HMI Products are calibrated science measurements computed from level-1 HMI filtergrams. We call these products "Observables" since, for the science goals of HMI, these are the basic observed physical quantities needed as input to specialized science processing. |
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| Level 1 HMI data products include . Line of sight velocity . MagneticField . Line of sight magnetic field . VectorMagneticField . Continuum Intensity . Line Depth |
Level 1.5 Observables include . Line of Sight products from both Camera1 (12m) and Camera2 (45s) . Doppler velocity . [:MagneticField: Magnetic field] . Continuum proxy . Line width . Line depth . Synoptic Maps . [:VectorMagneticField: Vector field products] from Camera1 (720s = 12m) . Stokes parameters I,Q,U,V at 6 wavelengths . Vector field inversions based on the Milne-Eddington approximations . Vector field, disambiguated |
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| The pipeline to produce these products relies on modules described briefly at ["HMIModuleTable"] | |
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| Summary of Magnetic Pipeline Modules ["HMIModuleTableSummary"] | |
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| The pipeline to produce these products relies on modules described briefly at ["HMIModuleTable"] | ==== Processing Errors & Quality Bits ==== If an error occurs during the processing of level-0 data into level-1 data, a corresponding bit is set in the "Quality Flag". This flag is implemented as a bit field which is stored in the QUALITY keyword. Each processing level has its own QUALITY keyword and copies of the lower level QUALITY keywords where appropriate. |
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| Summary of Magnetic Pipeline Modules [HMIModuleTableSummary"] | The bit assignments for QUALITY are found at: . [http://jsoc.stanford.edu/doc/data/hmi/Quality_Bits/quallev0_bits.txt HMI level-0 QUALITY] . [http://jsoc.stanford.edu/doc/data/hmi/Quality_Bits/quallev1_bits.txt HMI Level-1 QUALITY] . [:Lev1qualBits: HMI Observables QUALITY] |
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| ==== Processing Version Information ==== A keyword for calibration version keywords are included in level-1 data (CALVER32) through higher level products (CALVER64) starting in August 2012. This keyword is, at the start, considered to be a set of fields consisting of single hexidecimal digits. The presently assigned values are from least significant nibble: ||Field||bits||mask||name||Note|| ||0|| 0-3 || 0x0F ||HFCORRVR || Height of formation code version used to find disk center. Vers 2 for all data to date.|| || 1|| 4-7 || 0xF0 ||CROTA2VR || Version of CROTA2 in the Master pointing table. Vers 0 prior to Transit of Venus, then 1.|| A value of all bits set in a field signifies missing information. The default value of CALVER64 is 0xFFFFFFFFFFFFFFFF. |
Level 1+ HMI Data Products
HMI "Level-1" products are simply the individual filtergrams from level-0 but with flat-field images applied and fits to the limb computed to find the disk centerposition. Also ancillary metadata in included, such as SDO velocity and location from the SDO Flight Dynamics Service.
Level 1.5 HMI Products are calibrated science measurements computed from level-1 HMI filtergrams. We call these products "Observables" since, for the science goals of HMI, these are the basic observed physical quantities needed as input to specialized science processing.
Level 1.5 Observables include
- Line of Sight products from both Camera1 (12m) and Camera2 (45s)
- Doppler velocity
[:MagneticField: Magnetic field]
- Continuum proxy
- Line width
- Line depth
- Synoptic Maps
[:VectorMagneticField: Vector field products] from Camera1 (720s = 12m)
- Stokes parameters I,Q,U,V at 6 wavelengths
- Vector field inversions based on the Milne-Eddington approximations
- Vector field, disambiguated
The pipeline to produce these products relies on modules described briefly at ["HMIModuleTable"]
Summary of Magnetic Pipeline Modules ["HMIModuleTableSummary"]
Processing Errors & Quality Bits
If an error occurs during the processing of level-0 data into level-1 data, a corresponding bit is set in the "Quality Flag". This flag is implemented as a bit field which is stored in the QUALITY keyword. Each processing level has its own QUALITY keyword and copies of the lower level QUALITY keywords where appropriate.
The bit assignments for QUALITY are found at:
[http://jsoc.stanford.edu/doc/data/hmi/Quality_Bits/quallev0_bits.txt HMI level-0 QUALITY]
[http://jsoc.stanford.edu/doc/data/hmi/Quality_Bits/quallev1_bits.txt HMI Level-1 QUALITY]
[:Lev1qualBits: HMI Observables QUALITY]
Processing Version Information
A keyword for calibration version keywords are included in level-1 data (CALVER32) through higher level products (CALVER64) starting in August 2012. This keyword is, at the start, considered to be a set of fields consisting of single hexidecimal digits. The presently assigned values are from least significant nibble:
Field |
bits |
mask |
name |
Note |
0 |
0-3 |
0x0F |
HFCORRVR |
Height of formation code version used to find disk center. Vers 2 for all data to date. |
1 |
4-7 |
0xF0 |
CROTA2VR |
Version of CROTA2 in the Master pointing table. Vers 0 prior to Transit of Venus, then 1. |
A value of all bits set in a field signifies missing information. The default value of CALVER64 is 0xFFFFFFFFFFFFFFFF.
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