bin 光照曲线后的 Lightkurve nan 值

Question

我正在使用 lightkurve 2.0.2 库与 Python 3.8.5 和 astropy 4.2 来处理系外行星凌日。但是，当我想将光曲线分类为固定数量的点时，light_curve.flux 中除前两个之外的所有值都是 nan。我做错了什么？

import lightkurve as lk

tp = lk.search_targetpixelfile("Kepler-10", mission="Kepler", exptime="long", quarter=1).download()
lc = tp.to_lightcurve().flatten().remove_outliers()
fold = lc.fold(0.837)
bin = fold.bin(n_bins=101)

print(bin.flux)  # [0.99999749 0.99999977 nan nan nan nan nan nan nan ... nan nan nan nan]

Answer 1

在您的例子中，分箱是根据 fold 变量的时间数据完成的。我们来看看数据：

print(fold)

# =>          time                flux        ... 
#                             electron / s    ... 
#     -------------------- ------------------ ... 
#     -0.41839904743025785 0.9999366372082438 ... 
#     -0.41790346068516393 0.9999900469016064 ... 
#     -0.41710349403700253  1.000098604170269 ... 
#                      ...                ... ... 
#      0.41749621545238175 1.0000351718333538 ... 
#       0.4178061659377394 1.0000272820282354 ... 
#      0.41829640771343823 1.0000199004079346 ...

这意味着我们有大约 -0.4 天到 0.4 天的数据。

然后使用 bin = fold.bin(n_bins=101) 完成装箱。关于 bin 方法参数的文档（截断）：

   time_bin_size : `~astropy.units.Quantity`, float
       The time interval for the binned time series.
       (Default: 0.5 days; default unit: days.)
   time_bin_start : `~astropy.time.Time`, optional
       The start time for the binned time series. Defaults to the first
       time in the sampled time series.
   n_bins : int, optional
       The number of bins to use. Defaults to the number needed to fit all
       the original points. Note that this will create this number of bins
       of length ``time_bin_size`` independent of the lightkurve length.

您只传递了n_bins参数。这意味着，该方法将从 -0.4 开始创建 101 个宽度为 0.5 的 bin。所以第一个 bin 从 -0.4 到 0.1，第二个从 0.1 到 0.6，第三个从 0.6 到 1.1，...

现在很明显只有前两个 bin 包含数据。

而不是 n_bins，使用 bins:

   bins : int
       The number of bins to divide the lightkurve into. In contrast to
       ``n_bins`` this sets the length of ``time_bin_size`` accordingly.

这是结果：

bin = fold.bin(bins=101)
print(bin.flux) 

# => [1.0000268  1.00003322 1.00001914 1.00001018 1.00000905 1.00002073
#     0.99999502 1.00000155 1.0000071  0.99999901 1.000028   0.99998768
#     0.99998992 1.00003623 1.00001132 1.00005118 0.99998819 1.00001886
#     ...
#     1.00001082 1.00004898 1.0000009  1.00001234 1.00000681] electron / s

bins 参数在 lightkurve 2.0.2 中不可用，但在 2.0.6 中可用（感谢@Michal）。

bin 光照曲线后的 Lightkurve nan 值

Lightkurve nan values after bin light curve

python

astronomy

astropy