光照曲线后的nan值

Question

我使用Python3.8.5和astropy4.2的浅色 2.0.2库来处理系外行星过境。然而，当我想要将光曲线转到固定数目的点时，除前两个值外，light_curve.flux中的所有值都是nan。我做错什么了？

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，绑定是基于fold变量的时间数据完成的。让我们看一看数据：

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-0.4天到0.4天的数据。

然后使用bin = fold.bin(n_bins=101)完成绑定。有关bin方法的参数的文档(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n_bins参数。这意味着，该方法将创建101个从-0.4开始宽度为0.5的回收箱。所以第一个垃圾桶从-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，只有前两个回收箱包含数据。

不要使用n_bins，而是使用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.

其结果是：

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Lightkurve2.0.2中不可用，但在2.0.6中可用(谢谢@Michal)。