Here is a list of all namespaces with brief descriptions:

Nast [external]
Nastshim [external]
Nboost [external]
Nconf [external]
Nlsst [external]
Nafw [external]
Nbase [external]
Ncoadd [external]
Ncpputils [external]
Ndaf [external]
Ngdb [external]
Ngeom [external]
Nip [external]
Nlog [external]
Nmeas [external]
Npex [external]
Npipe
Ntasks
N_fallback_asinhmapping
NassociationUtils
Nbackground
NcalexpCutout
Ncalibrate
NcalibrateImage
NcharacterizeImage
Ncli
N_get_cli_subcommands
Ncmd
Ncommands
Nopt
Narguments
NcoaddBase
NcoaddInputRecorder
Ncolorterms
NcomputeExposureSummaryStats
NconsolidateSsTables
NcosmicRayPostDiff
NdataFrameActions
N_actions
N_baseDataFrameActions
N_evalColumnExpression
NdeblendCoaddSourcesPipeline
Ndiff_matched_tract_catalog
NdiffractionSpikeMask
NdrpAssociationPipe
NdrpDiaCalculationPipe
NexampleStatsTasks
Nextended_psf
Nextended_psf_candidates
Nextended_psf_cutout
Nextended_psf_fit
Nextended_psf_image
Nextended_psf_stack
Nextended_psf_subtract
NfinalizeCharacterization
Nfit_coadd_multiband
Nfit_coadd_psf
Nfit_multiband
NforcedPhotDetector
Nfunctors
NgenerateEphemerides
NgetRegionTimeFromVisit
NhealSparseMapping
NhealSparseMappingProperties
Nhips
NinsertFakes
NinterpImage
NisolatedStarAssociation
NloadReferenceCatalog
NmakeDiscreteSkyMap
Nmatch_tract_catalog
Nmatch_tract_catalog_probabilistic
NmatchBackgrounds
NmatchDiffimSourceInjected
NmeasurementDriver
NmeasurePsf
NmergeDetections
NmergeMeasurements
Nmetrics
NmpSkyEphemerisQueryDRP
NmultiBand
NmultiBandUtils
NobjectMasks
NpeekExposure
NphotoCal
Npostprocess
NprettyPictureMaker
N_colorMapper
N_equalizers
N_functors
N_bounds_remapper
N_color_scale
N_exposure_fusion
N_gamut_fixer
N_local_contrast
N_lum_scale
N_localContrast
N_plugins
N_task
N_utils
Ntypes
NprocessCcdWithFakes
NpropagateSourceFlags
NquickFrameMeasurement
NregisterImage
Nrepair
NreserveIsolatedStars
Nrewrite_images
N_rewrite_cell_coadd
N_rewrite_difference_image
N_rewrite_visit_image
Nrgb2hips
N_all_sky_hips
N_high_order_hips
N_low_order_hips
N_properties
N_utils
NscaleZeroPoint
NschemaUtils
Nscript
NmakeDiscreteSkyMap
NregisterDcrSubfilters
NregisterSkymap
NselectImages
NsimpleAssociation
NskyCorrection
NsnapCombine
Nsplit_primary
NssoAssociation
Nssp
Nephem
Nfelis
Nmoid
Nphotfit
Nschema
Nssobject
Nsssource
Nutil
NsspAuxiliaryFile
Nstatistic
NtractBackground
Nversion
NvisualizeVisit
Nshapelet [external]
Nskymap [external]
Nsphgeom [external]
NlsstDebug [external]
Nlsstimport [external]
Nndarray [external]
Npybind11 [external]
NshowVisitSkyMap [external]
Nstd	STL namespace