delta_attributes

Summary:

This file contains auxiliar output from the picca delta extraction: summary statistics of the computed deltas.

Naming Convention:

delta_attributes.fits.gz or delta_attributes_iterationITERATION.fits.gz, where ITERATION is the iteration step.

Regex:

delta_attributes(_iteration[0-9]+)?\.fits\.gz

File Type:

FITS

Contents

Number	EXTNAME	Type	Contents
HDU0	PRIMARY	PRIMARY	Empty
HDU1	STACK_DELTAS	BINTABLE	Delta mean properties
HDU2	VAR_FUNC	BINTABLE	Variance fitted functions
HDU3	CONT	BINTABLE	Mean quasar continuum
HDU4	FIT_METADATA	BINTABLE	Extra fit metadata

FITS Header Units

HDU0

This HDU has no non-standard required keywords.

Empty HDU.

HDU1

EXTNAME = STACK_DELTAS

Delta mean properties

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	24	int	table width
NAXIS2	2716	int	number of wavelenght pixels
FITORDER	1	int	order of the fit
CHECKSUM	UaQGWRQDUXQDUXQD	str	HDU checksum updated 2023-05-20T00:44:43
DATASUM	288651377	str	data unit checksum updated 2023-05-20T00:44:43

Required Data Table Columns

Name	Type	Units	Description
LOGLAM	float64	log(Angstrom)	log(wavelength)
STACK	float64		mean(1+delta)
WEIGHT	float64		Mean weight

HDU2

EXTNAME = VAR_FUNC

Variance fitted functions

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	48	int	table width
NAXIS2	20	int	number of wavelenght pixels
CHECKSUM	9l7aGj7V9j7ZGj7Z	str	HDU checksum updated 2023-05-20T00:44:43
DATASUM	2321635470	str	data unit checksum updated 2023-05-20T00:44:43

Required Data Table Columns

Name	Type	Units	Description
LOGLAM	float64	log(Angstrom)	log(wavelength)
ETA	float64		Intrinsic variace of fluctuations
VAR_LSS	float64		Mean weight
FUDGE	float64		ad-hoc term correcting varianc of high SNR quas
NUM_PIXELS	int32		Number of pixels in the fit
VALID_FIT	logical		Indicates valid fit

HDU3

EXTNAME = CONT

Mean quasar continuum

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	84	int	table width
NAXIS2	206	int	number of rest-frame pixels
CHECKSUM	nadFnWaFnaaFnUaF	str	HDU checksum updated 2023-05-20T00:44:43
DATASUM	2310375264	str	data unit checksum updated 2023-05-20T00:44:43

Required Data Table Columns

Name	Type	Units	Description
LOGLAM_REST	float64	log(Angstrom)	Logarithm of the rest-frame wavelength
MEAN_CONT	float64	10**-17 erg/(s cm2 Angstrom)	Mean quasar continuum
WEIGHT	float64		mean weight

HDU4

EXTNAME = FIT_METADATA

Mean quasar continuum

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	43	int	table width
NAXIS2	23168	int	number of forests
CHECKSUM	WIaqZHaoWHaoWHao	str	HDU checksum updated 2023-05-20T00:44:43
DATASUM	179646866	str	data unit checksum updated 2023-05-20T00:44:43

Required Data Table Columns

Name	Type	Units	Description
LOS_ID	int64		PICCA unique target ID
ZERO_POINT	float64		Continuum zero-point paramter
SLOPE	float64		Continuum slope parameter
CHI2	float64		Continuum fit chi2
NUM_DATAPOINTS	int64		Number of wavelenth pixels
ACCEPTED_FIT	logical		Fit acceptance

Notes and Examples

These files are generated with https://github.com/igmhub/picca/blob/master/bin/picca_delta_extraction.py The code was run twice:

picca_delta_extraction.py config/delta_extraction_ciii_step_1.ini
picca_delta_extraction.py config/delta_extraction_lya.ini