Example #1
0
def fix_lup_to_maggie(lup,
                      lup_sig,
                      photo_err=SDSS.photo_err,
                      abfix=SDSS.abfix):
    """
    Convert SDSS database ugriz luptitude (asinh mag) to AB maggie

    This function is different from lup_to_maggie in that it corrects
    erratic entries.  It also adds a photometric calibration
    uncertainties and applies a correction to adjust to AB photometry.

    REFERENCE
  
    k_sdssfix.pro of kcorrect v4_1_4
    """
    # the following line should set ivar to zero if sigma <= 0, which
    # is basically what k_sdss_err2ivar.pro does.
    lup_ivar = sigma2ivar(lup_sig)
    mask = np.equal(lup, -9999.) * np.not_equal(lup_ivar, 0.)
    lup_ivar = np.where(mask, 0., lup_ivar)
    lup_sig = ivar2sigma(lup_ivar)
    maggie, maggie_ivar = lup_to_maggie(lup, lup_sig)
    mask = np.equal(lup_ivar, 0.)
    maggie = np.where(mask, 0., maggie)
    maggie_ivar = np.where(mask, 0., maggie_ivar)
    # add photometric calibration errors
    maggie_ivar = add_absigma_to_maggie_ivar(maggie, maggie_ivar, photo_err)
    # correct for AB offsets
    abfix = np.asarray(abfix, dtype=FTYPE)
    maggie = maggie * 10**(-0.4 * abfix)
    maggie_ivar = maggie_ivar * 10**(0.8 * abfix)
    return maggie, maggie_ivar
Example #2
0
def fix_lup_to_maggie(lup, lup_sig, photo_err=SDSS.photo_err, abfix=SDSS.abfix):
    """
    Convert SDSS database ugriz luptitude (asinh mag) to AB maggie

    This function is different from lup_to_maggie in that it corrects
    erratic entries.  It also adds a photometric calibration
    uncertainties and applies a correction to adjust to AB photometry.

    REFERENCE
  
    k_sdssfix.pro of kcorrect v4_1_4
    """
    # the following line should set ivar to zero if sigma <= 0, which
    # is basically what k_sdss_err2ivar.pro does.
    lup_ivar = sigma2ivar(lup_sig)
    mask = np.equal(lup, -9999.) * np.not_equal(lup_ivar, 0.)
    lup_ivar = np.where(mask, 0., lup_ivar)
    lup_sig = ivar2sigma(lup_ivar)
    maggie, maggie_ivar = lup_to_maggie(lup, lup_sig)
    mask = np.equal(lup_ivar, 0.)
    maggie = np.where(mask, 0., maggie)
    maggie_ivar = np.where(mask, 0., maggie_ivar)
    # add photometric calibration errors
    maggie_ivar = add_absigma_to_maggie_ivar(maggie, maggie_ivar, photo_err)
    # correct for AB offsets
    abfix = np.asarray(abfix, dtype=FTYPE)
    maggie = maggie * 10**(-0.4 * abfix)
    maggie_ivar = maggie_ivar * 10**(0.8 * abfix)
    return maggie, maggie_ivar
Example #3
0
def lup_to_maggie(lup, lup_sig=[], sdss_filters='ugriz', bvalues=SDSS.bvalues):
    """
    Convert luptitude (asinh mag) to AB maggie

    Conversion from luptitude to maggie is:

    maggie = 2 b sinh( - ln(b) - 0.4 ln(10) lup)

    This is linear when maggie ~ b, identical to maggie for maggie >> b.

    Conversion of the errors is:

    maggie_err = 2 b cosh( -ln(b) - 0.4 ln(10) lup) (0.4 ln 10) lup_err
    
    This function returns AB maggies for the given set of SDSS
    filters.  If lup_sig is also given, the function returns the
    inverse variances of AB maggies.  The size of each entry in the
    input luptitude list must be the same as the number of SDSS
    filters specified in sdss_filters as a string (e.g., 'ugriz',
    'urz', etc.).

    REFERENCE

    k_lups2maggies.pro of kcorrect v4_1_4

    INPUT

    lup -- List of SDSS luptitudes
    lup_sig -- 1 sigma uncertanties in luptitudes
    sdss_filters -- SDSS filters as a string; defaults to 'ugriz'
    bvalues -- Softening 'b' parameters; defaults to SDSS.bvalues
    """
    # check input data
    lup, lup_sig = np.atleast_2d(lup), np.atleast_2d(lup_sig)
    if len(sdss_filters) != lup.shape[1]:
        raise ValueError('Input lup size incompatible with sdss_filters.')

    # get bvalues
    bvalues = dict(zip(SDSS.names, bvalues))
    b = np.zeros(len(sdss_filters), dtype=FTYPE)
    for i in range(len(sdss_filters)):
        b[i] = bvalues[sdss_filters[i]]

    # compute maggie
    maggie = 2. * b * np.sinh(-np.log(b) - 0.4 * np.log(10.) * lup)
    if lup_sig.size != 0:
        # uncertainties given, so compute the ivar of maggies
        if lup.shape != lup_sig.shape:
            raise ValueError('Array size different for lup and lup_sig.')
        maggie_sigma = (2. * b *
                        np.cosh(-np.log(b) - 0.4 * np.log(10.) * lup) * 0.4 *
                        np.log(10.) * lup_sig)
        return maggie, sigma2ivar(maggie_sigma)

    return maggie
Example #4
0
def lup_to_maggie(lup, lup_sig=[], sdss_filters='ugriz', bvalues=SDSS.bvalues):
    """
    Convert luptitude (asinh mag) to AB maggie

    Conversion from luptitude to maggie is:

    maggie = 2 b sinh( - ln(b) - 0.4 ln(10) lup)

    This is linear when maggie ~ b, identical to maggie for maggie >> b.

    Conversion of the errors is:

    maggie_err = 2 b cosh( -ln(b) - 0.4 ln(10) lup) (0.4 ln 10) lup_err
    
    This function returns AB maggies for the given set of SDSS
    filters.  If lup_sig is also given, the function returns the
    inverse variances of AB maggies.  The size of each entry in the
    input luptitude list must be the same as the number of SDSS
    filters specified in sdss_filters as a string (e.g., 'ugriz',
    'urz', etc.).

    REFERENCE

    k_lups2maggies.pro of kcorrect v4_1_4

    INPUT

    lup -- List of SDSS luptitudes
    lup_sig -- 1 sigma uncertanties in luptitudes
    sdss_filters -- SDSS filters as a string; defaults to 'ugriz'
    bvalues -- Softening 'b' parameters; defaults to SDSS.bvalues
    """
    # check input data
    lup, lup_sig = np.atleast_2d(lup), np.atleast_2d(lup_sig)
    if len(sdss_filters) != lup.shape[1]:
        raise ValueError('Input lup size incompatible with sdss_filters.')

    # get bvalues
    bvalues = dict(zip(SDSS.names, bvalues))
    b = np.zeros(len(sdss_filters), dtype=FTYPE)
    for i in range(len(sdss_filters)):
        b[i] = bvalues[sdss_filters[i]]

    # compute maggie
    maggie = 2. * b * np.sinh(-np.log(b) - 0.4 * np.log(10.) * lup)
    if lup_sig.size != 0:
        # uncertainties given, so compute the ivar of maggies
        if lup.shape != lup_sig.shape:
            raise ValueError('Array size different for lup and lup_sig.')
        maggie_sigma = (2. * b * np.cosh(-np.log(b) - 0.4 * np.log(10.) * lup)
                        * 0.4 * np.log(10.) * lup_sig)
        return maggie, sigma2ivar(maggie_sigma)

    return maggie