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16. Januar 2024







Spectrum

The reduction pipeline v2 produces two output fits files. The main output of the reduction pipeline is a spectrum and this is stored in a fits file (Sci_...sp_ech_main.fits). The fits file has two extensions. In the first extension, only the image header is contained with informations for and from the reduction. In the second extension, the data are stored as a binary table with an own header. The format of this table is:

Name Dimension Description
WAVE (Pixel, Relative order) Wavelength array of each order
SPEC_BLZ (Pixel, Relative order) Blaze normalised spectrum of each order
BLAZE (Pixel, Relative order) Blaze function (flat field spectrum) of each order
SIG (Pixel, Relative order) Signal to noise of each order
SPEC_NORM (Pixel, Relative order) Normalised spectrum of each order
WAVE_MERG (Pixel) Merged wavelength
SPEC_MERG (Pixel) Merged blaze normalised spectrum
F_SPEC_MERG (Pixel) Error of the merged blaze normalised spectrum
SPEC_MERG_NORM (Pixel) Merged normalised spectrum
F_SPEC_MERG_NORM (Pixel) Error of the merged normalised spectrum
INST_RESP_FUNC (Pixel) Instrumental response function
RESPONCE_CURVE_DAY_VAR (Pixel) Correction of the small scale variations in the spectrum


for a spectrum with one exposure and for spectrum with multi exposures with a very low S/N in the single exposure. For a spectrum based on multi exposures, the format is:

Name Dimension Description
WAVE (Pixel, Relative order) Wavelength array of each order
SPEC_BLZ (Pixel, Relative order) Blaze normalised spectrum of each order
BLAZE (Pixel, Relative order) Blaze function (flat field spectrum) of each order
SIG (Pixel, Relative order) Signal to noise of each order
SPEC_NORM (Pixel, Relative order) Normalised spectrum of each order
SINGLE_OBS_SPEC (Spectrum,Pixel, Relative order) Array with the single spectrum of each order
WAVE_MERG (Pixel) Merged wavelength
SPEC_MERG (Pixel) Merged blaze normalised spectrum
F_SPEC_MERG (Pixel) Error of the merged blaze normalised spectrum
SPEC_MERG_NORM (Pixel) Merged normalised spectrum
F_SPEC_MERG_NORM (Pixel) Error of the merged normalised spectrum
INST_RESP_FUNC (Pixel) Instrumental response function
RESPONCE_CURVE_DAY_VAR (Pixel) Correction of the small scale variations in the spectrum

The secondary output is a small fits file. The notation is Sci_...sp_ech_small.fits. This file include only the blaze normalised spectrum. This file is readable in IRAF or in FV without problems.
If one use the IDL read procedure readheros.pro than is the output a table with the columns wavelength and flux.

The format of the pipline v1 output one can find here.