# GOSAT_FTS_L1b_band3s

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `GOSAT_FTS_L1b_band3s` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime | double | {time} | [seconds since 2000-01-01] | start time of the measurement
longitude | double | {time} | [degree_east] | longitude of the measurement
latitude | double | {time} | [degree_north] | latitude of the measurement
radiance | double | {time, spectral} | [V/cm^-1] | radiances derived by taking the norm of the fourier transform of measured wavelengths
wavenumber | double | {time, spectral} | [cm^-1] | wavenumber for each point in the spectrum
index | int32 | {time} |  | zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for `GOSAT_FTS_L1b` products.

option name | legal values | description
--- | --- | ---
band | 1p, 1s, 2p, 2s, 3p, 3s, 4 | spectral band to ingest (default is 1p)

This definition is only applicable when: band=3s

## Mapping description

The table below details where and how each variable was retrieved from the input product.

field name | mapping description
--- | ---
datetime | path | /exposureAttribute/pointAttribute/Time[]
description | the record with year/month/day/hour/min/sec values is converted to a double precision floating point value that represents the amount of seconds since 2000-01-01 00:00:00
longitude | path | /exposureAttribute/pointAttribute/geometricInfo/centerLon[]
latitude | path | /exposureAttribute/pointAttribute/geometricInfo/centerLat[]
radiance | path | /Spectrum/SWIR/band3/obsWavelength[,1,,]
description | the radiance returned is the complex norm of the complex value that is stored in the product; in other words, what is returned is sqrt(real * real + imag * imag)
wavenumber | path | /exposureAttribute/pointAttribute/RadiometricCorrectionInfo/spectrumObsWavelengthRange_SWIR
description | the wavenumbers are calculated by evaluating the function a.x + b for x = 0 .. N-1 with a,b the wavelength range parameters in the product