Add JWST photometry correction

[gbrammer]

As of late August 2022, a number of groups have found that there still seem to be large corrections to the individual NIRCam SCA photometric calibration required, even after the CRDS updates in late July. There is a series of ongoing calibration programs that will establish the absolute calibration of all of the modes at high precision. For now, however, those calibration data are incomplete.

I have derived some corrections to the jwst_0942.pmap context using the following:

1. The flux calibration standard J1743045 suggests that the absolute NIRISS calibration is quite good, with just a correction of 1/1.04 required for F200W
2. The flux standard also suggests that NIRCam LW broadbands are fairly well calibrated, perhaps with the exception of a 1/0.912 correction needed for F444W
3. The flux standard data are currently only available for the B module in some filters. To calibrate the A module and also the additional broadband SW filters, I derived relative corrections using the wealth of data taken of the LMC astrometric calibration field, where certain patches of the field have been observed by more than one NIRCam SCA. The corrections are derived by measuring photometry in the NIRISS broad bands and then calculating scale factors of all of the NIRCam SW SCAs relative to these.
4. Relative A/B corrections for the NIRCam LW broad-band filters are also derived from the LMC data.

The tabulated values in grizli/data/photom_correction.yml are the median ratios of the derived flux densities in the indicated filters to some reference, either relative or absolute. To apply the corrections relative to exposures calibrated with the current CRDS_CONTEXT, the values should be divided from the SCI and ERR arrays, which is now implemented in utils.drizzle_from_visit.

The LMC mosaics are available at https://s3.amazonaws.com/grizli-v2/JwstMosaics/lmc-astrometric-field/lmc.html. The full notebook used to derive the LMC corrections is at https://s3.amazonaws.com/grizli-v2/JwstMosaics/lmc-astrometric-field/astrometric-field-photometry.ipynb.

The figures below show the distribution of flux ratios in the NIRCam LW and SW filters, where the median values are stored in the correction table.

Module ratios for NIRCam LW

NIRCam SW ratios relative to NIRISS

The multiplicative corrections are summarized below:

# det filt  pupil  mjsr_0942    gbr    ila  mjsr_gbr
# mjsr_0942 : PHOTMJSR from jwst_0942.pmap
# gbr : multiplicative corrections from G. Brammer
# ila : multiplicative corrections from I. Labbe
# mjsr_gbr = gbr * mjsr_0942
NRCA1 F090W CLEAR      3.762  0.826   ---   3.108
NRCA1 F115W CLEAR      3.299  0.914  0.876  3.014
NRCA1 F150W CLEAR      2.460  0.936  0.895  2.303
NRCA1 F200W CLEAR      2.211  0.865  0.846  1.913
NRCA2 F090W CLEAR      3.872  0.833   ---   3.224
NRCA2 F115W CLEAR      3.395  0.908  0.867  3.084
NRCA2 F150W CLEAR      2.531  0.937  0.894  2.371
NRCA2 F200W CLEAR      2.275  0.889  0.857  2.023
NRCA3 F090W CLEAR      4.026  0.762   ---   3.066
NRCA3 F115W CLEAR      3.531  0.862  0.840  3.044
NRCA3 F150W CLEAR      2.632  0.878  0.852  2.310
NRCA3 F200W CLEAR      2.366  0.800  0.794  1.892
NRCA4 F090W CLEAR      3.839  0.753   ---   2.891
NRCA4 F115W CLEAR      3.366  0.813  0.784  2.738
NRCA4 F150W CLEAR      2.509  0.837  0.811  2.100
NRCA4 F200W CLEAR      2.256  0.791  0.778  1.785
NRCB1 F090W CLEAR      3.874  0.894   ---   3.463
NRCB1 F115W CLEAR      3.397  0.959  0.897  3.258
NRCB1 F150W CLEAR      2.532  0.946  0.906  2.394
NRCB1 F200W CLEAR      2.276  0.873  0.866  1.987
NRCB2 F090W CLEAR      4.009  0.842   ---   3.377
NRCB2 F115W CLEAR      3.515  0.897  0.870  3.154
NRCB2 F150W CLEAR      2.621  0.896  0.879  2.348
NRCB2 F200W CLEAR      2.356  0.829  0.847  1.953
NRCB3 F090W CLEAR      3.706  0.914   ---   3.386
NRCB3 F115W CLEAR      3.250  0.995  0.933  3.234
NRCB3 F150W CLEAR      2.423  0.986  0.936  2.388
NRCB3 F200W CLEAR      2.178  0.901  0.888  1.963
NRCB4 F090W CLEAR      3.769  0.818   ---   3.085
NRCB4 F115W CLEAR      3.305  0.831  0.811  2.746
NRCB4 F150W CLEAR      2.464  0.849  0.822  2.092
NRCB4 F200W CLEAR      2.215  0.812  0.795  1.799
NRCBLONG F277W CLEAR   0.422  1.000   ---   0.422
NRCALONG F277W CLEAR   0.433  1.107   ---   0.480
NRCBLONG F356W CLEAR   0.372  1.000   ---   0.372
NRCALONG F356W CLEAR   0.381  1.088   ---   0.415
NRCBLONG F410M CLEAR   0.811  1.000  1.031  0.811
NRCALONG F410M CLEAR   0.832  1.053  1.031  0.876
NRCBLONG F444W CLEAR   0.335  1.096  1.031  0.367
NRCALONG F444W CLEAR   0.343  1.136  1.031  0.390

[gbrammer]

Some pretty pictures seeing background galaxies through the LMC


.

[gbrammer]

More complete numbers are now available in CRDS in jwst_0989.pmap. Here is an updated table of my multiplicative corrections to 0942 compared to the new values.

# det filt  pupil  mjsr_0942    gbr    ila  mjsr_gbr  file gbr_inv mjsr_0989 file_0989  ratio_989_gbr
# mjsr_0942 : PHOTMJSR from jwst_0942.pmap
# gbr : multiplicative corrections from G. Brammer
# ila : multiplicative corrections from I. Labbe
# mjsr_gbr = gbr * mjsr_0942
# 0942 numbers from jwst_nircam_photom_0[file].fits
# mjsr_0989 : PHOTMJSR from jwst_0989.pmap
# 0989 numbers from jwst_nircam_photom_0[file_0989].fits
# ratio_989_gbr = mjsr_0989 / mjsr_gbr
NRCA1 F090W CLEAR      3.762  0.826   ---   3.108     106 1.210    2.996 116  0.964
NRCA1 F115W CLEAR      3.299  0.914  0.876  3.014     106 1.094    2.963 116  0.983
NRCA1 F150W CLEAR      2.460  0.936  0.895  2.303     106 1.068    2.251 116  0.978
NRCA1 F200W CLEAR      2.211  0.865  0.846  1.913     106 1.155    1.892 116  0.989
NRCA2 F090W CLEAR      3.872  0.833   ---   3.224     100 1.201    3.282 110  1.018
NRCA2 F115W CLEAR      3.395  0.908  0.867  3.084     100 1.101    3.101 110  1.006
NRCA2 F150W CLEAR      2.531  0.937  0.894  2.371     100 1.067    2.384 110  1.005
NRCA2 F200W CLEAR      2.275  0.889  0.857  2.023     100 1.125    2.081 110  1.029
NRCA3 F090W CLEAR      4.026  0.762   ---   3.066     102 1.313    2.954 112  0.963
NRCA3 F115W CLEAR      3.531  0.862  0.840  3.044     102 1.160    2.949 112  0.969
NRCA3 F150W CLEAR      2.632  0.878  0.852  2.310     102 1.139    2.204 112  0.954
NRCA3 F200W CLEAR      2.366  0.800  0.794  1.892     102 1.251    1.828 112  0.966
NRCA4 F090W CLEAR      3.839  0.753   ---   2.891     105 1.328    2.910 115  1.007
NRCA4 F115W CLEAR      3.366  0.813  0.784  2.738     105 1.229    2.776 115  1.014
NRCA4 F150W CLEAR      2.509  0.837  0.811  2.100     105 1.195    2.102 115  1.001
NRCA4 F200W CLEAR      2.256  0.791  0.778  1.785     105 1.264    1.805 115  1.012
NRCB1 F090W CLEAR      3.874  0.894   ---   3.463     108 1.119    3.564 118  1.029
NRCB1 F115W CLEAR      3.397  0.959  0.897  3.258     108 1.043    3.272 118  1.004
NRCB1 F150W CLEAR      2.532  0.946  0.906  2.394     108 1.058    2.412 118  1.008
NRCB1 F200W CLEAR      2.276  0.873  0.866  1.987     108 1.145    2.022 118  1.018
NRCB2 F090W CLEAR      4.009  0.842   ---   3.377     107 1.187    3.427 117  1.015
NRCB2 F115W CLEAR      3.515  0.897  0.870  3.154     107 1.114    3.128 117  0.992
NRCB2 F150W CLEAR      2.621  0.896  0.879  2.348     107 1.117    2.305 117  0.982
NRCB2 F200W CLEAR      2.356  0.829  0.847  1.953     107 1.206    1.952 117  0.999
NRCB3 F090W CLEAR      3.706  0.914   ---   3.386     103 1.095    3.425 113  1.012
NRCB3 F115W CLEAR      3.250  0.995  0.933  3.234     103 1.005    3.186 113  0.985
NRCB3 F150W CLEAR      2.423  0.986  0.936  2.388     103 1.015    2.352 113  0.985
NRCB3 F200W CLEAR      2.178  0.901  0.888  1.963     103 1.110    1.957 113  0.997
NRCB4 F090W CLEAR      3.769  0.818   ---   3.085     099 1.222    3.043 109  0.987
NRCB4 F115W CLEAR      3.305  0.831  0.811  2.746     099 1.204    2.698 109  0.983
NRCB4 F150W CLEAR      2.464  0.849  0.822  2.092     099 1.178    2.029 109  0.970
NRCB4 F200W CLEAR      2.215  0.812  0.795  1.799     099 1.231    1.771 109  0.985
NRCBLONG F277W CLEAR   0.422  1.000   ---   0.422     104 1.000    0.417 114  0.989
NRCALONG F277W CLEAR   0.433  1.107   ---   0.480     101 0.903    0.491 111  1.024
NRCBLONG F300M CLEAR   0.952  1.000   ---   0.952     104 1.000    0.949 114  0.997
NRCALONG F300M CLEAR   0.977  1.059   ---   1.035     101 0.944    1.013 111  0.979
NRCBLONG F356W CLEAR   0.372  1.000   ---   0.372     104 1.000    0.376 114  1.011
NRCALONG F356W CLEAR   0.381  1.088   ---   0.415     101 0.919    0.405 111  0.976
NRCBLONG F410M CLEAR   0.811  1.042  1.031  0.845     104 0.960    0.875 114  1.036
NRCALONG F410M CLEAR   0.832  1.031  1.031  0.858     101 0.970    0.870 111  1.015
NRCBLONG F444W CLEAR   0.335  1.096  1.031  0.367     104 0.912    0.373 114  1.015
NRCALONG F444W CLEAR   0.343  1.136  1.031  0.390     101 0.880    0.393 111  1.007
NRCA1 F140M CLEAR      5.380  1.000   ---   5.380     106 1.000    5.075 116  0.943
NRCA1 F182M CLEAR      3.788  1.000   ---   3.788     106 1.000    3.490 116  0.921
NRCA1 F210M CLEAR      4.678  1.000   ---   4.678     106 1.000    4.404 116  0.941
NRCA1 F150W2 F162M     5.106  1.000   ---   5.106     106 1.000    4.663 116  0.913
NRCA2 F140M CLEAR      5.537  1.000   ---   5.537     100 1.000    5.355 110  0.967
NRCA2 F182M CLEAR      3.898  1.000   ---   3.898     100 1.000    3.779 110  0.970
NRCA2 F210M CLEAR      4.814  1.000   ---   4.814     100 1.000    4.841 110  1.006
NRCA2 F150W2 F162M     5.255  1.000   ---   5.255     100 1.000    5.007 110  0.953
NRCA3 F140M CLEAR      5.758  1.000   ---   5.758     102 1.000    5.011 112  0.870
NRCA3 F182M CLEAR      4.053  1.000   ---   4.053     102 1.000    3.375 112  0.833
NRCA3 F210M CLEAR      5.006  1.000   ---   5.006     102 1.000    4.235 112  0.846
NRCA3 F150W2 F162M     5.464  1.000   ---   5.464     102 1.000    4.516 112  0.827
NRCA4 F140M CLEAR      5.489  1.000   ---   5.489     105 1.000    4.714 115  0.859
NRCA4 F182M CLEAR      3.864  1.000   ---   3.864     105 1.000    3.328 115  0.861
NRCA4 F210M CLEAR      4.773  1.000   ---   4.773     105 1.000    4.223 115  0.885
NRCA4 F150W2 F162M     5.210  1.000   ---   5.210     105 1.000    4.371 115  0.839
NRCB1 F140M CLEAR      5.539  1.000   ---   5.539     108 1.000    5.441 118  0.982
NRCB1 F182M CLEAR      3.900  1.000   ---   3.900     108 1.000    3.776 118  0.968
NRCB1 F210M CLEAR      4.816  1.000   ---   4.816     108 1.000    4.760 118  0.988
NRCB1 F150W2 F162M     5.257  1.000   ---   5.257     108 1.000    5.068 118  0.964
NRCB2 F140M CLEAR      5.733  1.000   ---   5.733     107 1.000    5.196 117  0.906
NRCB2 F182M CLEAR      4.036  1.000   ---   4.036     107 1.000    3.592 117  0.890
NRCB2 F210M CLEAR      4.984  1.000   ---   4.984     107 1.000    4.517 117  0.906
NRCB2 F150W2 F162M     5.440  1.000   ---   5.440     107 1.000    4.804 117  0.883
NRCB3 F140M CLEAR      5.300  1.000   ---   5.300     103 1.000    5.324 113  1.005
NRCB3 F182M CLEAR      3.731  1.000   ---   3.731     103 1.000    3.627 113  0.972
NRCB3 F210M CLEAR      4.608  1.000   ---   4.608     103 1.000    4.562 113  0.990
NRCB3 F150W2 F162M     5.029  1.000   ---   5.029     103 1.000    4.891 113  0.973
NRCB4 F140M CLEAR      5.390  1.000   ---   5.390     099 1.000    4.557 109  0.846
NRCB4 F182M CLEAR      3.794  1.000   ---   3.794     099 1.000    3.268 109  0.861
NRCB4 F210M CLEAR      4.686  1.000   ---   4.686     099 1.000    4.137 109  0.883
NRCB4 F150W2 F162M     5.115  1.000   ---   5.115     099 1.000    4.269 109  0.835
NRCBLONG F250M CLEAR   1.632  1.000   ---   1.632     104 1.000    1.646 114  1.008
NRCALONG F250M CLEAR   1.673  1.000   ---   1.673     101 1.000    1.679 111  1.004
NRCBLONG F335M CLEAR   0.851  1.000   ---   0.851     104 1.000    0.851 114  1.000
NRCALONG F335M CLEAR   0.873  1.000   ---   0.873     101 1.000    0.989 111  1.133
NRCBLONG F360M CLEAR   0.870  1.000   ---   0.870     104 1.000    0.878 114  1.009
NRCALONG F360M CLEAR   0.892  1.000   ---   0.892     101 1.000    0.929 111  1.041

[gbrammer]

And a figure comparing the relative

and absolute values for SW Wide filters

and absolute values in LW filters

[gbrammer]

If you use these numbers or want to refer to this discussion, please cite https://doi.org/10.5281/zenodo.7143382.