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M11-STELIB TEMPLATE LIBRARY
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From README_M11.txt:
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THIS README DESCRIBES THE FILES CONTAINING THE STELLAR POPULATION MODELS
OF MARASTON & STROMBACK (2011, MNRAS). MODELS ARE AVAILABLE AT
WWW.MARASTON.EU/M11/.
 
These models have the same stellar energetics and atmospheric parameters
as the standard Maraston (2005, M05) models. The difference is in the
individual stellar spectra that are assigned to the various synthetic
stars according to their effective temperatures and gravities (Teff and
log). These spectra can be either empirical or theoretical, and in some
cases a mixture of them. 

In particular, the empirically-based models have been extended in
wavelength coverage into the UV, using the high-resolution models
published in Maraston et al. (2009, 493, 425), which are based on the
theoretical spectral library UVBLUE (Rodrigues-Merino et al. 2005). This
extension was made at various metallicities in case of the MILES-based
models, and at solar metallicity for STELIB and ELODIE.  The UV-extended
models will be indicated using the addition 'UVextended' to the file
name (see below).

We also provide a version of the Pickles-based models, which extend to
the UV, using the models with the theoretical UV. In this case since is
not an extension we call then 'UVtheoretical'.

In general, models should be chosen according to the spectral resolution
that is needed by observations, though differences induced by the use of
different spectral libraries exist.  See the paper for a description or
contact the authors. 

GENERAL NAMING:

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ssp_M11'_'library'_'any eventual extension'.'imf''zxxx'.'HB morphology': 
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  * 'ssp_M11': Simple Stellar Populations by Maraston & Stromback  2011

  * 'library': reference to the adopted stellar library, e.g. Pickles,
    MILES, STELIB, ELODIE,   MARCS, see below for a detailed
    description. 					
  
  * 'any eventual extension': it refers to whether the models have been
                              extended in wavelength coverage by merging
                              with other models or have been revised
                              with respect to the original library.
                              Cases are:

     'UVextended': models extended into the UV by merging with
                   theoretically-based SSPs

     'UVtheoretical': only for Pickles-based models. The Pickles-based
                      UV as been substituted with the theoretical UV
     'nearIRextended': 
     'revisednearIRslope': only for MILES-based models of solar
                           metallicity. The slope of the models longward
                           6000 AA has been slightly revised as
                           described in the Appendix of the paper.

  * 'imf': Initial Mass Funcion,IMF, namely:

    '.ss' ==> Salpeter IMF
    '.kr' ==> Kroupa IMF
    '.cha' ==> Chabrier IMF

    (Other IMFs could be obtained contacting the authors)

  * 'zxxx': chemical composition, as it follows (notation identical to
            M05)

     z10m4=0.0001
     z0001=0.001
     z001=0.01
     z002=0.02 (solar metallicity)
     z004=0.04 	

  *  'Horizontal Branch morphology': following the notation of M05 this
                                     can be rhb=intermediate-red and
                                     bhb=intermediate-blue. Relevant to
                                     sub-solar metallicities.


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STELIB-BASED MODELS: These models are based on the stellar library
                     STELIB by Le Borgne et al. (2003).

                  * Cool high-resolution theoretical stars (Gustafsson
                    et al. 2008) have been added to counter inadequacies
                    in the STELIB library. 

                  * Many spectra in the library are not complete over
                    the quoted wavelength
                    range, which limits the actual wavelength range of
                    the youngest ages at solar, and all ages at
                    non-solar metallicities.

                  * Somewhat coarse sampling of stellar parameter space
                    at non-solar metallicities may affect the
                    reliability of these models.

			        Resolution: 3.1-3.4 AA (fwhm)
			        0.5 AA sampling


ssp_M11_STELIB.'imf'z001: 24 ages, 200 Myr to 15 Gyr
				          3201.0 - 9296.5 AA
				          12192 flux points
				          !Usable wavelength range for all ages is
				            3201.0 - 7900.0 AA!

ssp_M11_STELIB_UVextended.ssz001: 21 ages, 200 Myr to 12 Gyr
				                  1001.0 - 9296.5 AA
				                  16952 flux points

                                  !Usable wavelength range for all ages
                                    is 1001.0 - 7900.0 AA!

ssp_M11_STELIB.'imf'z002: 39 ages, 30 Myr to 15 Gyr
				          3201.0 - 9296.5 AA
				          12192 flux points

ssp_M11_STELIB_UVextended.ssz002: 36 ages, 30 Myr to 12 Gyr
				                  1001.0 - 9296.5 AA 
				                  16592 flux points
                                  UV-extended version, models merged
                                      around 3750 AA.

ssp_M11_STELIB.'imf'z004: 22 ages, 400 Myr to 15 Gyr
				          3201.0 - 9296.5 AA
				          12192 flux points
				          !Usable wavelength range for all ages is
                            3201.0 - 7900.0 AA!

ssp_M11_STELIB_UVextended.ssz004: 18 ages, 400 Myr to 12 Gyr
				                  1001.0 - 9296.5 AA
				                  16952 flux points
                                  !Usable wavelength range for all ages
                                    is 1001.0 - 7900.0 AA!

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DAP NOTES:

This library only contains the following templates:

    ssp_M11_MILES.ss.z001
    ssp_M11_MILES.ss.z002
    ssp_M11_MILES.ss.z004

Given the following warning regarding the spectral range of the
non-solar metallicity templates:

!Usable wavelength range for all ages is 3201.0 - 7900.0 AA!

ALL templates have been limited to this wavelength range.

The original library has a sampling of 0.5 A/pixel, and a FWHM of the
resolution element of 3.1 angstroms.  I resampled this to 1 A/pixel to
reduce the oversampling of the spectra.

IMPORTANT:

The resampled spectra are named *_s.fits; the original spectra do not
have the _s suffix.  When constructing the library to fit the spectra,
only the *_s.fits spectra are read.

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K.B. Westfall, 24 Mar 2015
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