## Content

The Bruzual-Charlot Atlas is a library of galaxy spectra computed by Bruzual and Charlot using their Isochrone Synthesis Spectral Evolutionary Code. The December 1995 version of the atlas consists of 21 instantaneous bursts characterized by different IMF slope functions, and mass limits. Each instantaneous burst contains 221 spectral energy distributions (SEDs) corresponding to 221 time steps from 0 to 20 Gyr. To get to the on-line spectral templates go to TRDS-BC95 ATLAS.

To learn all the details about the content of this library and how to generate specific spectral templates consult the README file in the directory.

The on-line library of SEDs consists of 84 FITS files. All SEDs have been obtained using the original binary bc95*.ised files and the program galaxevpl as explained in the README file.

The on-line SEDs represent bursts characterized by a Salpeter initial mass function (IMF) with different ranges in lower and upper mass limits, and at several ages (10E5, 25E5, 50E5, 76E5, 10E6, 25E6, 50E6, 10E7, 50E7, 10E8, 50E8, 10E9 years) after the burst. SEDs for instantaneous and composite bursts are available. Each SED has 1187 wavelength points covering the 100 angstroms to 100 microns wavelength range, and the fluxes are given in units of solar luminosity per Angstrom. The nebular contribution to the spectral energy distribution, i.e. emission lines and nebular continuum, is not include in the SEDs.

A list of the on-line SEDs, and corresponding file names, is given in the table below. In the file name, the "xxxx" indicates the age of the burst. For example, the file bc95_d_50E5.fits contains the SED for a five million years old instantaneous burst characterized by a Salpeter IMF with lower and upper mass limits of 2.5 and 125 solar masses, respectivelly.

#### Table 1: Characteristics of the on-line Bruzual-Charlot SEDs

File name IMF Lower Mass
(solar mass)
Upper Mass
(solar mass)
Notes
bc95_a_XXXX Salpeter 0.1 125 instantaneous
bc95_b_XXXX Salpeter 0.1 65 instantaneous
bc95_c_XXXX Salpeter 0.1 30 instantaneous
bc95_d_XXXX Salpeter 2.5 125 instantaneous
bc95_e_XXXX Salpeter 0.1 125 burst lasting 1Gyr
bc95_f_XXXX Salpeter 0.1 125 exp. decreasing SFR with
e-folding time of 1Gyr
bc95_g_XXXX Salpeter 0.1 125 constant SFR of 1E-10 $$M_{solar}$$/yr