Calibration Version keywords - CALVER32 and CALVER64

Keywords describing the HMI calibration version have been included in level-1 data (CALVER32) and higher level products (CALVER64) starting in August 2012. This keyword is a set of fields consisting of single hexidecimal digits. Each nibble has a meaning described in the following table.

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.

2

8-11

0xF00

N/A

If > 0, then smooth look-up tables were used to produce observables

3

12-15

0xF000

N/A

If > 0, then a correction for non-linearity of the CCDs was applied. If 0x1000, the polynomial coefficients used for this correction are: -8.2799134,0.017660396,-3.7157499e-06,9.0137137e-11 (for the side camera) and -11.081771,0.017383740,-2.7165221e-06,6.9233459e-11 (for the front camera). If 0x2000, the polynomial coefficients used for this correction are: 0.0,0.025409177,-4.0088672e-06,1.0615198e-10 (side camera) and 0.0,0.020677687,-3.1873243e-06,8.7536678e-11 (front camera)

4

16-19

0xF0000

N/A

If 0, then observing sequence was 'mod C'; mod C was the standard observing sequence before 2016.04.13_19:12:55.11_UTC, FSN=104683793.

See Calver64ModLNote

If 2 then original deprecated Mod L processing

Also see Note 2

If 3 then mod-L misalignment corrected

If 4 then misalignment and filtergram selection correct

5

20-23

0xF00000

N/A

If > 0 then PSF/scattered light deconvolution has been done, 1==CUDA version, 2== C version

6

24-27

0xF000000

N/A

If > 0, then a rotational flat field was used. The code in HMI_observables and HMI_IQUVaveraging checks only on the bit 0x1000000 (originally field 4 was used for this, changed in Nov 2016)

7

28-31

0xF0000000

N/A

If > 0, then the observer location keywords have been updated. 0x1, bit 28, means CRLN_OBS and HGLN_OBS if present have been corrected. See ObserverLocationCorrection

The default value of CALVER64 is 0 and should never be seen so long as QUALITY >= 0. The concept of a missing value for a CALVERxx field does not make sense since CALVERxx refers to the version of code or source of values vs the decisions made by that code. If for instance the limb fit fails in lev1 processing, HFCORRVR still should contain the code version but the appropriate QUALITY bit should show that that code could not produce a useful value. Higher level products may propagate CALVER64. If a new product record is made from multiple input records then that code must decide the range of input CALVER that are acceptable and if different versions are OK for the output product, which value to forward. A good choice would be to send forward the lowest level from the input records to indicate that older versions were used in the output product. This could be used later to decide which products should be updated when the input series itself is updated.

Notes

JSD entries for CALVER32 and CALVER64:

Prior to Aug 2012 hmi.lev1 had a keyword named HFCORRVR which can be taken as correct for fields 0 and 1 except that a 0 in the first nibble (field 0) should be changed to 2 to match the other records made with same code.

In the process of adding CALVER64 and CALVER32 for existing records these keywords should be set to 0x12 when updated with the post-Transit-of-Venus CROTA2 values. The plan for doing the August 2012 update is described at Crota2UpdatePlan.

Starting 1 Oct 2012 fields 2 and 3 are populated. The older data have not been reprocessed (as of 15 Jan 2013).

Note 2: Mod-C and Mod-L Processing

hmi.S_720s users:

Regular use of the HMI mod-L frame list began at 2016.04.13_19:12:55 (fns=104683793). Mod-L requires use of filtergrams from both HMI cameras to compute the Stokes vector products, hmi.S_720s. Errors in the Mod-L processing were discovered in July and September 2017 that were fixed in September and October 2017. Reprocessing was completed by 18 February 2018. Details are provided at Calver64ModLNote.

JsocWiki: CalibrationVersions (last edited 2020-10-01 08:25:49 by PhilScherrer)