Abstract The near-Earth asteroid (3200) Phaethon is regarded as the parent body of the Geminid meteor stream. It is also an active asteroid with a very blue spectrum which is similar to that of the members of the Pallas family. For obtaining this asteroid’s surface property in more detail, we conducted a series of multicolor photometry of this asteroid over a wide range of solar phase angle during its close approach to the Earth in the end of 2017. Our observations confirmed that Phaethon is a C-complex asteroid as previous studies have claimed. We also obtained the phase curve for this asteroid in solar phase angle of 22.67 ∼ 114.48 degrees. From this result, we estimate that the absolute magnitude (H) of this asteroid is 14.450±0.017 mag, and its phase slope is (β) ∼0.0423±0.0005. Using the absolute magnitude that we estimated, together with an estimate of Phaethon’s albedo (0.122 ± 0.03) that previous literature derived, we can derived the Phaethon’s diameter, 4. \mathrm{90}_{-0.54}ˆ{+0.79} km. The diameter estimate is roughly consistent with what was observed through the radar ranging measurement conducted as the same period as our observation.

中文翻译：

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鲁林天文台（3200）法厄同光度观测研究

摘要 近地小行星（3200）法厄同被认为是双子座流星流的母体。它也是一颗活跃的小行星，具有与帕拉斯家族成员相似的蓝色光谱。为了更详细地获得这颗小行星的表面特性，我们在这颗小行星于 2017 年底接近地球时，在较宽的太阳相位角范围内对其进行了一系列多色测光。我们的观察证实 Phaethon 是一颗 C-正如之前的研究声称的那样复杂的小行星。我们还得到了这颗小行星在太阳相角为 22.67 ∼ 114.48 度的相位曲线。根据这个结果，我们估计这颗小行星的绝对星等 (H) 为 14.450±0.017 mag，其相位斜率为 (β) ∼0.0423±0.0005。使用我们估计的绝对幅度，结合先前文献推导出的法厄同反照率估计值 (0.122 ± 0.03)，我们可以推导出法厄同的直径，4. \mathrm{90}_{-0.54}ˆ{+0.79} km。直径估计与通过与我们观察相同时期进行的雷达测距测量所观察到的大致一致。