Here is a list of all namespaces with brief descriptions:

Nast [external]
Nastshim [external]
Nboost [external]
Ngeometry
Ntraits
Nserialization [external]
Nconf [external]
Nlsst [external]
Nafw
NcameraGeom
N_amplifier
N_assembleImage
N_camera
N_cameraFactory
N_cameraGeomEnumDicts
N_detector
N_detectorCollection
N_makePixelToTanPixel
N_rotateBBoxBy90
N_transformConfig
NcameraConfig
Npupil
NtestUtils
Nutils
Ncoord
N_refraction
Ndetection
N_footprintContinued
N_footprintMerge
N_heavyFootprintContinued
N_peak
Ndetail
Nmultiband
Nutils
Ndisplay
N_images_compat
N_write_fits
Nds9
Nds9Regions
Ninterface
Nrgb
N_rgbContinued
Nutils
NvirtualDevice
Nfits
N_fitsContinued
N_pickleFits
Ndetail
Nformatters
Ngeom
N_calculateSipWcsHeader
N_hpxUtils
N_python
N_transform
N_spanSetContinued
Ndetail
Ndetails
Nellipses
N_axes
N_ellipse
N_quadrupole
Ndetail
Npolygon
NskyWcs
NtestUtils
Ntransform
NtransformConfig
NtransformFactory
NtransformFromString
Nutils
NwcsUtils
Nimage
N_apCorrMap
N_apCorrMapContinued
N_basicUtils
N_coaddInputsContinued
N_exposure
N_exposureContinued
N_multiband
N_exposureInfoContinued
N_exposureSummaryStats
N_image
N_disableArithmetic
N_fitsIoWithOptions
N_image
N_mask
N_multiband
N_slicing
N_maskedImage
N_maskedImageContinued
N_photoCalibContinued
N_visitInfo
Ndetail
Ndetails
Nexposure
NexposureUtils
Nimpl
Npixel
Npython
NtestUtils
Nutils
Nmath
N_background
N_backgroundList
N_chebyshevBoundedField
N_chebyshevBoundedFieldConfig
N_spatialCell
N_warper
Ndetail
Ndetails
Nmultiband
Ntable
N_aggregates
N_aliasMap
N_arrays
N_base
N_baseColumnView
N_exposure
N_match
N_schema
N_schemaMapper
N_simple
N_source
NcatalogMatches
Ndetail
Nio
Npython
NmultiMatch
Npython
NtestUtils
Ntypehandling
N_GenericMap
N_SimpleGenericMap
Ndetail
Ntest
NtestUtils
Nversion
Nbase [external]
Ncpputils [external]
Ndaf [external]
Ngdb
Nafw
Nprinters
Ngeom [external]
Nlog [external]
Npex [external]
Nsphgeom [external]
NlsstDebug [external]
Nlsstimport [external]
Nndarray
Npybind11 [external]
Nstd	STL namespace