def getSourcesAndCoeffsFile(self, filename='DECam_xtalk_20130606.txt'):
"""File containing DECam crosstalk coefficients.
This text file is provided by NOAO in a particular format with
information about the DECam crosstalk coefficients. It is available at
http://www.ctio.noao.edu/noao/content/DECam-Calibration-Files
Parameters
----------
filename : `str`, optional
File containing the decam crosstalk coefficients, from NOAO.
Returns
-------
result : `str`
Full path to filename.
"""
mapper = DecamMapper()
packageName = mapper.getPackageName()
packageDir = getPackageDir(packageName)
return os.path.join(packageDir, 'decam', filename)
