SNLS First Year Data Release

May 12, 2006

This is a release of the lightcurve data of the 71 Type Ia supernovae analyzed during the first year of the CFHT Supernova Legacy Survey.

Note that the data provided here is not the final photometry since work is going on building deeper reference images and improving photometric pipeline and calibration (see the paper for a detailed description of the analysis).

Paper

Title : The Supernova Legacy Survey: measurement of Omega_M, Omega_Lambda and w from the 1st year data set

Authors : P. Astier, J. Guy, N. Regnault, R. Pain, E. Aubourg, D. Balam, S. Basa, R.G. Carlberg, S. Fabbro, D. Fouchez, I.M. Hook, D.A. Howell, H. Lafoux, J.D. Neill, N. Palanques-Delabrouille, K. Perrett, C. Pritchet, J. Rich, M. Sullivan, R. Taillet, G. Aldering, P. Antilogus, V. Arsenijevic, C. Balland, S. Baumont, J. Bronder, H. Courtois, R.S. Ellis, M. Filiol, A.C. Concalves, A. Goobar, D. Guide, D. Hardin, V. Lusset, C. Lidman, R. McMahon, M. Mouchet, A. Mourao, S. Perlmutter, P. Ripoche, C. Tao, N. Walton.

Reference : Astier et al., A&A 447, 31-48 (2006)

Grab a copy here : astro-ph/0510447

Download

Download the complete tar file : snls_photometric_data_1.1.tar.gz

Content

The above tar file contains a directory for each of the 71 SNLS Type Ia supernovae used in the paper. The data format is suited to be used directly with the light curve fitting package SALT. Each of those directories contains the following files:

Descriptor ("lightfile")

Contains some informations about this SN such as redshift and the expected excess of B-V due to extinction by dust in the Milky Way (key MWEBV).
Example (04D3fk/lightfile):
NAME 04D3fk
RA 14:18:26.198
Decl +52:31:42.74
Redshift 0.3578
MWEBV 0.007940

Light curve files ("lc2fit_{g,r,i,z}.dat")

There is one ASCII file for each light curve.
- 1st column, Date: date of the observations (Modified Julian Days)
- 2nd column, Flux: ADU counts for a reference observation
- 3rd column, Fluxerr: statistical error for the flux measurement (warning: the error is marginalized over the other flux measurements. It is advised to use the weight matrix).
- 4th column, ZP: zero point for the reference observation (see the calibration section for details).
Example (04D3fk/lc2fit_r.dat):
@BAND r
@INSTRUMENT MEGACAM
@MAGSYS VEGA
@SNLS_RELEASE 1.0
@WEIGHTMAT flux_per_night_weightmat_r.dat
# Date :
# Flux :
# Fluxerr :
# ZP :
# end
53094.590000 169.789 117.360 32.0829
53109.540000 1996.451 115.658 32.0829
53117.460000 7577.889 85.263 32.0829
53121.410000 9630.777 74.991 32.0829
53123.450000 10126.273 106.104 32.0829
53134.340000 9354.071 99.564 32.0829
53138.430000 7450.038 103.460 32.0829
53146.460000 4476.125 103.456 32.0829
53149.310000 3627.968 77.369 32.0829
53151.450000 3062.253 146.818 32.0829
53165.390000 1353.857 69.794 32.0829
53169.380000 1261.391 99.949 32.0829
53175.360000 1026.612 88.093 32.0829
53178.350000 1009.050 79.662 32.0829
53193.380000 832.421 167.942 32.0829
53197.340000 747.289 96.378 32.0829
53198.300000 841.802 117.526 32.0829
53204.350000 698.951 92.172 32.0829

Weight matrices ("flux_per_night_weightmat_{g,r,i,z}.dat")

Inverse of covariance matrix of measured fluxes. The two first numbers give the size (N,N) of the matrix. The rest in an array of values, vals(i+j*N) = M(i,j), where i=0 refers to the first measurement in the light curve.

About Calibration

The light curves were calibrated against a set of "tertiary standard stars" (see Astier et al., 2006 for details).
- The magnitudes of these stars define a Megacam natural system anchored to the Landolt catalog.
- Photometry was performed on these stars using the same PSF and in the same exposures as the supernova to derive a zero point, ZP defined as : -2.5 log(Flux) + ZP = mag
- Since Megacam filters differ significantly from those used by Landolt, there are large color terms between those two magnitude systems. However, one should not correct SN magnitudes using color terms derived from observations of stars but rather use directly the response functions of the instrument. The following effective response functions were used in the analysis. (wavelength in Angstrom, and efficiency in counts per photon, with arbitrary normalization).
effective_filter_g.dat
effective_filter_r.dat
effective_filter_i.dat
effective_filter_z.dat
These data were obtained by multiplying an atmospheric vapor absorption model, reflectivities, optical transmissions, filter transmissions and quantum efficiencies of the Megaprime detector. This model is consistent with observations using synthetic magnitudes and color--color diagrams with other instruments (see details in Astier et al., 2006) (for SALT users, these data are already available in the package).


Please reference to Astier et al. [SNLS Collaboration] A&A 447, 31-48 (2006) when using this data set.
For more information about this page and the content of the tar file, contact Julien Guy