Question about using cmodel and gaap packages in Gen3

Hi all,

Aaron @ameisner and I are testing using the cmodel and gaap packages in Gen3. We are using the LSST pipeline v23.1 to process DECam exposures. We generally followed the procedures in Lee Kevin’s note Merian Data Processing Using the LSST Science Pipelines - HackMD. We tried adding these into the config for forcedPhotCoadd.
obs_lsst/ at main · lsst/obs_lsst · GitHub
obs_lsst/ at main · lsst/obs_lsst · GitHub
It didn’t work for cmodel. The error is lsst::pex::exceptions::NotFoundError: 'Field with name 'modelfit_CModel_initial_instFlux' not found with type 'D'.' So we wonder if we also need to run cmodel in measure and mergeMeasurements for coadd images?
For gaap, it ran but gave warnings like - Cannot aperture correct ext_gaap_GaapFlux_1_15x_1_0 because could not find ext_gaap_GaapFlux_1_15x_1_0_instFlux or ext_gaap_GaapFlux_1_15x_1_0_instFluxErr in apCorrMap.
Does this mean we need to run gaap starting from CCD processing (for aperture correction)?
Any suggestions will be appreciated. Thank you.

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Unfortunately, I’m afraid so. You will need to run CharacterizeImageTask in CCD processing, and might need to run makeWarp and assembleCoadd steps as well, so that the aperture corrections are propagated to the coadds where measurements take place.