We analyzed the BVR photometry of comet C/2014 S2 obtained between March and June 2016, in observatories installed in Europe and the United States. Using the Lomb–Scargle periodogram, we found that the most probable periodicity deduced from the V-band magnitudes is 2.70 days, suggesting that it is the period of rotation of the nucleus of this comet is $$2.70 \pm 0.07$$2.70±0.07 days or $$68 \pm 2$$68±2 h, with a peak-to-peak light curve amplitude of $$0.4 \pm 0.1$$0.4±0.1 magnitudes. We verify that the absolute magnitude $$H_0$$H0 and the activity index n differ from each other when they are calculated from the visual or CCD magnitudes. Considering the absolute magnitude $$H_{v0}=$$Hv0= 6.0, obtained from visual magnitudes, we estimate that the lower limit of nuclear radius is 1.3 km. Analyzing the variation of magnitude R with the photometric aperture, we suggest that the coma of this object was in steady-state within the time limits of our observational interval. The coma had a mean color index B–V$$=0.79\pm 0.22$$=0.79±0.22, which is typical of active comets. Additionally, we have shown that the use of a variable photometric aperture, linked to geocentric distance, is probably unnecessary for the comet PANSTARRS .

中文翻译：

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近日点后彗星 C/2014 S2 (PANSTARRS) 的光度学研究

我们分析了 2016 年 3 月至 6 月期间在欧洲和美国安装的天文台中获得的彗星 C/2014 S2 的 BVR 光度测量。使用 Lomb-Scargle 周期图，我们发现从 V 波段星等推导出的最可能的周期是 2.70 天，这表明这颗彗星的原子核自转周期为 $$2.70 \pm 0.07$$2.70±0.07 天或 $$68 \pm 2$$68±2 h，峰峰值光变曲线幅度为 $$0.4 \pm 0.1$$0.4±0.1 级。我们验证了绝对震级 $$H_0$$H0 和活动指数 n 在根据视觉或 CCD 震级计算时彼此不同。考虑到从目视星等获得的绝对星等$$H_{v0}=$$Hv0= 6.0，我们估计核半径的下限为1.3 km。通过光度孔径分析星等 R 的变化，我们建议该物体的彗发在我们观测间隔的时间限制内处于稳态。彗发的平均颜色指数 B–V$$=0.79\pm 0.22$$=0.79±0.22，这是活跃彗星的典型特征。此外，我们已经表明，对于 PANSTARRS 彗星来说，使用与地心距离相关的可变光度孔径可能是不必要的。