delta-HEALPIX
- Summary:
This file contains the main output from the picca delta extraction: the lyman alpha transmission fluctuations for all analysed quasars in a given healpix
- Naming Convention:
delta-HEALPIX.fits, whereHEALPIXis the healpix id.- Regex:
delta-[0-9]+\.fits\.gz- File Type:
FITS
Contents
Number |
EXTNAME |
Type |
Contents |
|---|---|---|---|
PRIMARY |
PRIMARY |
Empty |
|
LAMBDA |
IMAGE |
Wavelength grid |
|
METADATA |
BINTABLE |
Per forest metadata |
|
DELTA |
IMAGE |
Flux transmission field |
|
WEIGHT |
IMAGE |
Weights |
|
CONT |
IMAGE |
Quasar continua |
FITS Header Units
HDU0
This HDU has no non-standard required keywords.
Empty HDU.
HDU1
EXTNAME = LAMBDA
Wavelength grid
Required Header Keywords
Required Header Keywords Table
KEY |
Example Value |
Type |
Comment |
|---|---|---|---|
NAXIS1 |
2716 |
int |
number of wavelength pixels |
WAVE_SOLUTION |
lin |
str |
chosen wavelength solution |
DELTA_LAMBDA |
0.8 |
float |
pixel step |
BUNIT |
Angstrom |
str |
wavelength units |
CHECKSUM |
UZ3aaZ2aVZ2aaZ2a |
str |
HDU checksum |
DATASUM |
1634060384 |
str |
HDU data checksum |
Data: FITS image [float64, 2716]
HDU2
EXTNAME = METADATA
Per-forest metadata
Required Header Keywords
Required Header Keywords Table
KEY |
Example Value |
Type |
Comment |
|---|---|---|---|
NAXIS1 |
84 |
int |
table width |
NAXIS2 |
340 |
int |
number of forests |
BLINDING |
none |
str |
blinding scheme used |
CHECKSUM |
UZ3aaZ2aVZ2aaZ2a |
str |
HDU checksum |
DATASUM |
1634060384 |
str |
HDU data checksum |
Required Data Table Columns
Name |
Type |
Units |
Description |
|---|---|---|---|
LOS_ID |
int64 |
PICCA unique target ID |
|
RA |
float64 |
rad |
Target Right Ascension [radians] |
DEC |
float64 |
rad |
Target declination [radians] |
Z |
float64 |
Redshift |
|
MEANSNR |
float64 |
mean signal-to-noise ratio |
|
TARGETID |
int64 |
Unique target ID |
|
NIGHT |
char[12] |
Observation night(s) |
|
PETAL |
char[12] |
Observation petal(s) |
|
TILE |
char[12] |
Observation tile(s) |
HDU3
EXTNAME = DELTA
Flux transmission field in wavelength bins
Required Header Keywords
Required Header Keywords Table
KEY |
Example Value |
Type |
Comment |
|---|---|---|---|
NAXIS1 |
2716 |
int |
number of wavelength pixels |
NAXIS2 |
340 |
int |
number of forests |
BUNIT |
str |
delta units (unitless) |
|
CHECKSUM |
UZ3aaZ2aVZ2aaZ2a |
str |
HDU checksum |
DATASUM |
1634060384 |
str |
HDU data checksum |
Data: FITS image [float64, 2716x340]
HDU4
EXTNAME = WEIGHT
Weights in wavelength bins
Required Header Keywords
Required Header Keywords Table
KEY |
Example Value |
Type |
Comment |
|---|---|---|---|
NAXIS1 |
2716 |
int |
number of wavelength pixels |
NAXIS2 |
340 |
int |
number of forests |
CHECKSUM |
UZ3aaZ2aVZ2aaZ2a |
str |
HDU checksum |
DATASUM |
1634060384 |
str |
HDU data checksum |
Data: FITS image [float64, 2716x340]
HDU5
EXTNAME = CONT
Quasar continuum in wavelength bins
Required Header Keywords
Required Header Keywords Table
KEY |
Example Value |
Type |
Comment |
|---|---|---|---|
NAXIS1 |
2716 |
int |
number of wavelength pixels |
NAXIS2 |
340 |
int |
number of forests |
BUNIT |
10**-17 erg/(s cm2 Angstrom) |
str |
quasar continuum units |
CHECKSUM |
UZ3aaZ2aVZ2aaZ2a |
str |
HDU checksum |
DATASUM |
1634060384 |
str |
HDU data checksum |
Data: FITS image [float64, 2716x340]
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