General information about FITS formatted files are in Sec 4.36.1 of
the SNANA manual: 
  https://github.com/RickKessler/SNANA/blob/master/doc/snana_manual.pdf
The training sample was generated with 40 cores, and thus there are 40
HEAD FITS files and 40 PHOT FITS files per model.

Here is more specific format information for the ELASTICC training set:

HEAD files:              
  SNANA-FITS name        alert name        description
# ------------------------------------------------------
* SNID                   diaObjectId       integer ID
* RA,DEC                 ra,decl           sky coordinates (degrees)
* NOBS                   nobs              number of obs (all bands)
* PTROBS_MIN             ---               points to 1st light curve obs in PHOT file
* PTROBS_MAX             ---               points to last light curve obs
* MWEBV[_ERR]            mwebv[_err]       E(B-V) for Milky way
* REDSHIFT_HELIO[_ERR]   z_final[_err]     best heliocentric redshift
                                            zSpec if available; else zPhot; else -9
* REDSHIFT_FINAL[_ERR]   ---               CMB redshift
* VPEC                   ---               0 +_ 300 km/sec (no correction)

* HOSTGAL_NMATCH         ---               number of host matches with DDLR < 4
* HOSTGAL_NMATCH2        ---               number of host matches with DDLR < 7
* HOSTGAL_RA             hostgal_ra        R.A. (deg) for center of host
* HOSTGAL_DEC            hostgal_dec       declination (deg) for center of host
* HOSTGAL_SNSEP          hostgal_snsep     transient-host separation, arcsec
* HOSTGAL_SPECZ          hostgal_zspec     zSpec of host if (-9 -> not available)
* HOSTGAL_SPECZ_ERR      hostgal_zspec_err uncertainty on zSpec
* HOSTGAL_PHOTOZ         hostgal_zphot     zphot (mean of PDF); -9 -> not available
* HOSTGAL_PHOTOZ_ERR     hostgal_zphot_err uncertainty on zphot (rms of zPDF)
* HOSTGAL_ZPHOT_Q[PPP]   hostgal_zphot_q[ppp]  redshift containing PPP% of zPDF prob
* HOSTGAL_MAG_[band]     hostgal_mag_[band]    host mags for band=u,g,r,i,z,Y
* HOSTGAL_MAGERR_[band]  hostgal_magerr_[band] uncertainty on above mags
    [Each hostgal_xxx has hostgal2_xxx 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]
    
* SIM_TYPE_INDEX         ---         true integer transient type (e.g., 1 for SNIa)
* SIM_[SSS]              ---         true sim property SSS

PHOT files:
* MJD                midPointTai      modified Julian date (-777 -> end of light curve)
* BAND               filterName       u,g,r,i,z, or Y
* PHOTFLAG           ---              bit-mask of information
                                        += 4096 for detection (roughly SNR>5)
					+= 2048 trigger (1st detection) -> PHOTFLAG=6144
                                        += 1024 saturation (>100,000 pe in central pixel)
* FLUXCAL            psFlux           calibrated flux :
                                          mag(SNANA sim)  = 27.5 - 2.5*log10(FLUXCAL)
					  mag(LSST-alert) = 31.4 - 2.5*log10(psFlux)
* FLUXCALERR         psFluxErr        Poisson uncertainty on FLUXCAL; sky+galaxy+source
* SIM_MAGOBS         ---              true model mag
     image properties
* PSF_SIG1           ---              PSF Gauss sigma, pixels
* SKY_SIG            ---              sky noise (ADU/pixel)
* ZEROPT             ---              image zero point
* GAIN               ---              N_photoelectron/ADU = 1.0