二维光谱银河数据的信噪比合并

Question

我有长缝摄谱仪拍摄的椭圆星系 NGC 4697 的 2D 光谱。x 方向（水平）对应于波长，y 方向对应于波长（垂直）对应于距星系中心的距离，而中间最亮的行是半径等于0的星系中心区域。由于我走得越远，信噪比就越差（增加y） ，我想将中心外信噪比较差的行合并在一起，以获得更好的信噪比，合并的一维光谱，我想稍后用于运动学光谱分析。

 def calc_signal_noise(lam, flux):
    '''calculate the signal to noise ratio of the galaxy spectra'''
    # cut out part of the spectrum without absorption features
    flux_section = flux[(lam >= 8.6075) & (lam <= 8.62)]
    lam_section = lam[(lam >= 8.6075) & (lam <= 8.62)]
    # fit polynom to the data in this part
    pol_coeff = np.polyfit(lam_section, flux_section, 5)
    pol_val = np.polyval(pol_coeff, lam_section)
    # calculate the rms error
    rms_error = np.std(pol_val-flux_section)
    signal_noise = np.median(flux_section/rms_error)
    return signal_noise

这是计算 S/N 比的函数，我现在想编写一个函数来对我的行进行装箱，直到获得所需的大约 50 的 S/N。

 def bin_spectra(data, cent_row, S_N_lim):
    """ bin spectra for different radii to achieve similar S/N for each binned spectra"""
    # variables:
    # data = 2 dimensional spectral data, where x-dir=wavelength and y-dir=distance from center, in our case data_gal
    # cent_row = int vor y-value (radius = 0 )
    # S_N_lim = minimal S/N ratio needed for spectral analysis
    # split data i
    data_upper = data()
    data_lower
    # Do I use the same wavelength array for all rows ?
    # extract 1D-spectrum for central row
    # take mean of more then 1 row to achieve better S/N ratio
    flux_gal_cent = data_gal[cent_row, :]  # first look on spectra in SAOImage ds9, row 597 corresponds to a central region
    w_gal = WCS(hdr_gal, naxis=1, relax=False, fix=False)
    loglam_gal = w_gal.wcs_pix2world(np.arange(len(flux_gal)), 0)[0]

    S_N = calc_signal_noise(loglam_gal, flux_gal_cent)

我不知道如何完成这个。我想从中心行开始，然后独立地从中心行向上和向下放置垃圾箱。如果我对行进行分箱/平均的信噪比达到约 50，我想将通量、波长、信噪比和距中心行的半径存储在 txt 文件中。

我有一个想法如何对多行进行平均：

flux_gal = np.mean(data_gal[n_row1:n_row2,:], 0) to get the mean of rows n_row1 through (n_row2 - 1)

并且我知道如何计算多行的半径：

radius = (n_row_center-np.mean(n_row1, n_row22))*0.2  #output in arcseconds

但我无法将其串成一个连贯的函数。关于编程方法或如何构造函数的任何提示都会对我有很大帮助。