qso_mgii-SURVEY-PROGRAM-PIXNUM.fits

Summary:

This file contains the output of the MgII fitter which is a classifier algorithm to collect spectra with MgII broad emission line.

Naming Convention:

qso_mgii-SURVEY-PROGRAM-PIXNUM.fits, where SURVEY is e.g. main or sv1, PROGRAM is e.g. bright or ``dark and PIXNUM is the HEALPixel number.

Regex:

qso_mgii-(cmx|main|special|sv1|sv2|sv3)-(backup|bright|dark|other)-[0-9]+\.fits

File Type:

FITS, 22 KB

Contents

Number	EXTNAME	Type	Contents
HDU0		IMAGE	Empty.
HDU1	MGII	BINTABLE	Output of MgII fitter.

FITS Header Units

HDU0

This HDU has no non-standard required keywords.

Empty HDU.

HDU1

EXTNAME = MGII

Output of MgII fitter.

Required Header Keywords

Required Header Keywords Table

KEY	Example Value	Type	Comment
NAXIS1	83	int	width of table in bytes
NAXIS2	154	int	number of rows in table

Required Data Table Columns

Name	Type	Units	Description
TARGETID	int64		Unique target ID
RA	float64		Target Right Ascension [degrees]
DEC	float64		Target declination [degrees]
Z_RR	float64		Redshift collected from redrock file
ZERR	float32		Redshift error from redrock file
IS_QSO_MGII	logical		Is the object pass the MgII selection ?
SV1_DESI_TARGET [1]	int64		Dark survey + calibration targeting bits for SV1
DESI_TARGET	int64		Dark survey + calibration targeting bits
SPECTYPE	char[10]		Spectype from redrock file
DELTA_CHI2	float32		Difference of chi2 between redrock fit and MgII fitter over the lambda interval considered during the fit [2]
A	float32		fitted parameter by MgII fitter [2] [3]
SIGMA	float32		fitted parameter by MgII fitter [2] [3]
B	float32		fitted parameter by MgII fitter [3]
VAR_A	float32		error on A [2]
VAR_SIGMA	float32		error on SIGMA
VAR_B	float32		error on B

[1]

Optional

[2] (1,2,3,4)

MgII selection is performed with these parameters. See: https://github.com/desihub/desispec/blob/720153babcf85dd93530252b0c1f631d48edfc0d/py/desispec/mgii_afterburner.py#L5

[3] (1,2,3)

MgII fitter use the following form: fit_function = lambda x, A, sigma, B : A * np.exp(-1.0 * (x)**2 / (2 * sigma**2)) + B See: https://github.com/desihub/desispec/blob/720153babcf85dd93530252b0c1f631d48edfc0d/py/desispec/mgii_afterburner.py#L283

Notes and Examples

These files are generated with https://github.com/desihub/desispec/blob/master/bin/desi_qso_mgii_afterburner

As mentioned on the top of the previous file, the MgII fitter is available here: https://github.com/desihub/desispec/blob/master/py/desispec/mgii_afterburner.py