0 - DATA: Transient light curves from DES-SN

Overview

The light-curves are produced using the Scene Modelling Photometry pipeline described in Brout et al. 2019a and Sanchez et al. 2024 (in prep.).

The full set of light-curves will be released after acceptance of Sanchez et al. 2024 (in prep.) currently in collaboration wide review.

Content datasets

We provide light-curves in 4 different directories:

• DES-SN5YR_DES: The SMP light curve dataset from DES 5YR

• DES-SN5YR_LOWZ: The Low-Z survey DES calibrated light curve data

• DES-SN5YR_Foundation: The Foundation survey DES calibrated light curve data

• DES-SN5YR_DES_DIFFIMG: The DIFFIMG, with PSF forced photometry over the entire dataset

Data Format

The light curve files are provided in standard FITS format following the SNANA convention. The data is split in HEAD.FITS files, just for the header information, and PHOT.FITS files containing the actual light curve measurements.

HEAD file

The HEAD file contains tabular information for all transient events and it stores the SNID that uniquely identifies the event. This integer type variable can be used to find the event light-curve and it is shared among all files in DES-SN5YR.

HEAD File Column variables

Variable name	Description
SNID	integer or character ID
FAKE	0=real data, 1=fake overlaid on image, 2=SNANA sim,
RA,DEC	sky coordinates (degrees)
SNTYPE	integer type assigned by survey (e.g., SPEC type)
NOBS	number of obs (all bands)
PTROBS_MIN	pointer to 1st light curve obs in PHOT file
PTROBS_MAX	pointer to last light curve obs
MWEBV[_ERR]	E(B-V) for Milky way
REDSHIFT_HELIO[_ERR]	best heliocentric redshift; zSpec if available; else zPhot; else -9
REDSHIFT_FINAL[_ERR]	best CMB redshift (no VPEC correction)
VPEC_[ERR]	pec velocity (km/sec) and error on correction
PEAKMJD	approx PEAKMJD; useful to init light curve fit
MJD_TRIGGER	MJD when survey trigger is satisfied
MJD_DETECT_FIRST	MJD of first detection
MJD_DETECT_LAST	MJD of last detection
HOSTGAL_SB_FLUXCAL_[band]	Surface brightness mag at SN location
HOSTGAL_NMATCH	number of host matches with DDLR < 4
HOSTGAL_NMATCH2	number of host matches with DDLR < 7
HOSTGAL_OBJID	integer id of host (long long int)
HOSTGAL_RA	R.A. (deg) for center of host
HOSTGAL_DEC	declination (deg) for center of host
HOSTGAL_SNSEP	transient-host separation, arcsec
HOSTGAL_DDLR	SN-host sep in distance-light-radii (d_DLR)
HOSTGAL_SPECZ[_ERR]	zSpec of host (-9 -> not available)
HOSTGAL_PHOTOZ[_ERR]	zphot (mean of PDF); -9 -> not available
HOSTGAL_ZPHOT_Q[PPP]	redshift containing PPP percent of zPDF prob
HOSTGAL_LOGMASS[_ERR]	logmass and error
HOSTGAL_LOGSFR[_ERR]	log(star formation rate) and error
HOSTGAL_MAG_[band]	Host Magnitudes for band=u,g,r,i,z,Y
HOSTGAL_MAGERR_[band]	Host magnitude error.
Additional variables for simulated data.
SIM_TYPE_INDEX	true integer transient type (e.g., 1 for SNIa)
SIM_[SSS]	true sim property SSS

Note

HOSTGAL_ quantities

• Each HOSTGAL_{} has HOSTGAL2_{} for 2nd host-match;

• -999 indicates no 2nd host; else values are filled.

• First listed host has smallest DDLR and may not be the true host

Note

Using data from the HOSTGAL quantities:

Please cite Kelsey et al. 2023 and Wiseman et al. 2020.

PHOT file

The PHOT file contains the light curve measurements, with all written sequentially to the PHOT-tables, and pointers in the HEAD file (see PTROBS_MIN and PTROBS_MAX) are used to select the appropriate rows from the PHOT table. To help catch pointer mistakes, MJD = -777 is written after each light curve to clearly indicate the end of it.

PHOT file variable columns

Variable name	Description
MJD	Float, Modified Julian Day (MJD).
BAND	String indicating DES bandpass filter. (g, r, i, z)
CCDNUM	CCD or detector number
IMGNUM	DES Image number identifier; e.g. exposure number, or visit id
FIELD	DES-SN survey field name. (SHALLOW, DEEP) (E1, E2, E3, S1, S2, X1, X2, X3, C1, C2)
PHOTFLAG	bit-mask of information (check data README)
PHOTPROB	float metric; e.g, RealBogus score, chi2, …
FLUXCAL	calibrated flux : mag = 27.5 - 2.5*log10(FLUXCAL)
FLUXCALERR	Poisson uncertainty on FLUXCAL; sky+galaxy+source
PSF_SIG1	PSF Gauss sigma, pixels
SKY_SIG	sky noise (ADU/pixel)
SKY_SIG_T	template sky noise (for DIFFIMG, not for SMP)
ZEROPT	image zero point
GAIN	N_photoelectron/ADU
XPIX	x-locaton on CCD (pixels)
YPIX	y-locaton on CCD (pixels)
Additional variables for simulated data.
SIM_MAGOBS	true model mag

SNTYPE nomeclature

The types as defined in our Data released photometry light-curves are:

HEAD file SNTYPE nomenclature

SNTYPE	Description
0	“NO_SPEC” (for the vast majority, no spectra obtained)
1	“SNIa”
101	“SNIa?”
3	“SNIax”
4	“SNIa-pec”
5	“SNI” (no H in spectrum, but cant distinguisn Ia vs Ib)
20	“SNIIP”
21	“SNIIL”
22	“SNIIn”
23	“SNIIb”
29	“SNII”
122	“SNIIn?”
129	“SNII?”
32	“SNIb”
33	“SNIc”
39	“SNIbc”
139	“SNIbc?”
41	“SLSN-I”
42	“SLSN-II”
66	“SLSN-II?”
141	“SLSN-I?”
80	“AGN”
81	“TDE”
82	“M-Star”
180	“AGN?”

---